diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index b3a0e1b757..d7ae669919 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -895,6 +895,39 @@ private static function processArrayTypes(array $arrayTypes): array
 			return [];
 		}
 
+		if (count($arrayTypes) > 1) {
+			// Keep list arrays separate from arrays whose keys are exclusively
+			// strings (and thus can never form a list). Merging the two would
+			// widen the key type to `int<0, max>|string` and lose the information
+			// that the integer keys come only from the list part — which in turn
+			// breaks narrowing the union via `array_is_list()`.
+			$listArrayTypes = [];
+			$stringKeyedArrayTypes = [];
+			$emptyArrayTypes = [];
+			$canSeparateLists = true;
+			foreach ($arrayTypes as $arrayType) {
+				if ($arrayType->isIterableAtLeastOnce()->no()) {
+					// The empty array is a subtype of both list and string-keyed
+					// arrays, so it never forces a separation on its own.
+					$emptyArrayTypes[] = $arrayType;
+				} elseif ($arrayType->isList()->yes()) {
+					$listArrayTypes[] = $arrayType;
+				} elseif ($arrayType->getIterableKeyType()->isString()->yes()) {
+					$stringKeyedArrayTypes[] = $arrayType;
+				} else {
+					$canSeparateLists = false;
+					break;
+				}
+			}
+
+			if ($canSeparateLists && $listArrayTypes !== [] && $stringKeyedArrayTypes !== []) {
+				return array_merge(
+					self::processArrayTypes($listArrayTypes),
+					self::processArrayTypes(array_merge($stringKeyedArrayTypes, $emptyArrayTypes)),
+				);
+			}
+		}
+
 		$accessoryTypes = self::processArrayAccessoryTypes($arrayTypes);
 
 		if (count($arrayTypes) === 1) {
diff --git a/tests/PHPStan/Analyser/nsrt/bug-14797.php b/tests/PHPStan/Analyser/nsrt/bug-14797.php
new file mode 100644
index 0000000000..538b4cddca
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-14797.php
@@ -0,0 +1,44 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14797;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param array<non-empty-string, non-empty-string>|list<non-empty-string> $values
+ */
+function toValues(array $values): void
+{
+	assertType('array<non-empty-string, non-empty-string>|list<non-empty-string>', $values);
+	if (!array_is_list($values)) {
+		assertType('array<non-empty-string, non-empty-string>', $values);
+	} else {
+		assertType('list<non-empty-string>', $values);
+	}
+}
+
+/**
+ * @param array<string, int>|list<int> $values
+ */
+function withString(array $values): void
+{
+	assertType('array<string, int>|list<int>', $values);
+	if (array_is_list($values)) {
+		assertType('list<int>', $values);
+	} else {
+		assertType('array<string, int>', $values);
+	}
+}
+
+/**
+ * @param array<int|string, int>|list<int> $values
+ */
+function stillMergeWhenIntKeysPossible(array $values): void
+{
+	// when the non-list part already allows integer keys, the integer keys
+	// are not exclusive to the list part, so we keep the merged form
+	assertType('array<int|string, int>', $values);
+	if (!array_is_list($values)) {
+		assertType('non-empty-array<int|string, int>', $values);
+	}
+}
diff --git a/tests/PHPStan/Rules/Arrays/data/bug-6000.php b/tests/PHPStan/Rules/Arrays/data/bug-6000.php
index c409cbfda1..db68dce1ae 100644
--- a/tests/PHPStan/Rules/Arrays/data/bug-6000.php
+++ b/tests/PHPStan/Rules/Arrays/data/bug-6000.php
@@ -9,7 +9,7 @@ function (): void {
 	$data = [];
 
 	foreach ($data as $key => $value) {
-		assertType('array<int<0, max>|string, array<string>|string>', $data[$key]);
+		assertType('array<string, array<string>|string>|list<string>', $data[$key]);
 		if ($key === 'classmap') {
 			assertType('list<string>', $data[$key]);
 			assertType('list<string>', $value);
diff --git a/tests/PHPStan/Rules/Arrays/data/bug-8467a.php b/tests/PHPStan/Rules/Arrays/data/bug-8467a.php
index bba055bf54..e58e1c40b7 100644
--- a/tests/PHPStan/Rules/Arrays/data/bug-8467a.php
+++ b/tests/PHPStan/Rules/Arrays/data/bug-8467a.php
@@ -27,7 +27,7 @@ public function foo (CompletePackageInterface $package): void {
 		if (\count($package->getAutoload()) > 0) {
 			$autoloadConfig = $package->getAutoload();
 			foreach ($autoloadConfig as $type => $autoloads) {
-				assertType('array<int<0, max>|string, array<string>|string>', $autoloadConfig[$type]);
+				assertType('array<string, array<string>|string>|list<string>', $autoloadConfig[$type]);
 				if ($type === 'psr-0' || $type === 'psr-4') {
 
 				} elseif ($type === 'classmap') {
diff --git a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
index f6196b99ca..19443eefed 100644
--- a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
@@ -876,7 +876,7 @@ public function testBug8146bErrors(): void
 		$this->checkBenevolentUnionTypes = true;
 		$this->analyse([__DIR__ . '/data/bug-8146b-errors.php'], [
 			[
-				"Method Bug8146bError\LocationFixtures::getData() should return array<non-empty-string, array<non-empty-string, array{constituencies: non-empty-list<non-empty-string>, coordinates: array{lat: float, lng: float, ...}}>> but returns array{Bács-Kiskun: array{Ágasegyháza: array{constituencies: array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}, coordinates: array{lat: 46.8386043, lng: 19.4502899}}, Akasztó: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.6898175, lng: 19.205086}}, Apostag: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.8812652, lng: 18.9648478}}, Bácsalmás: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1250396, lng: 19.3357509}}, Bácsbokod: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.1234737, lng: 19.155708}}, Bácsborsód: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.0989373, lng: 19.1566725}}, Bácsszentgyörgy: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 45.9746039, lng: 19.0398066}}, Bácsszőlős: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1352003, lng: 19.4215997}}, ...}, Baranya: non-empty-array<literal-string&non-falsy-string, non-empty-array<literal-string&non-falsy-string, non-empty-array<int<0, max>|(literal-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Békés: array{Almáskamarás: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4617785, lng: 21.092448}}, Battonya: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.2902462, lng: 21.0199215}}, Békés: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.6704899, lng: 21.0434996}}, Békéscsaba: array{constituencies: array{'Békés 1.'}, coordinates: array{lat: 46.6735939, lng: 21.0877309}}, Békéssámson: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4208677, lng: 20.6176498}}, Békésszentandrás: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.8715996, lng: 20.48336}}, Bélmegyer: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.8726019, lng: 21.1832832}}, Biharugra: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.9691009, lng: 21.5987651}}, ...}, Borsod-Abaúj-Zemplén: non-empty-array<literal-string&non-falsy-string, non-empty-array<literal-string&non-falsy-string, non-empty-array<int<0, max>|(literal-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Budapest: array{'Budapest I. ker.': array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.4968219, lng: 19.037458}}, 'Budapest II. ker.': array{constituencies: array{'Budapest 03.', 'Budapest 04.'}, coordinates: array{lat: 47.5393329, lng: 18.986934}}, 'Budapest III. ker.': array{constituencies: array{'Budapest 04.', 'Budapest 10.'}, coordinates: array{lat: 47.5671768, lng: 19.0368517}}, 'Budapest IV. ker.': array{constituencies: array{'Budapest 11.', 'Budapest 12.'}, coordinates: array{lat: 47.5648915, lng: 19.0913149}}, 'Budapest V. ker.': array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.5002319, lng: 19.0520181}}, 'Budapest VI. ker.': array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.509863, lng: 19.0625813}}, 'Budapest VII. ker.': array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.5027289, lng: 19.073376}}, 'Budapest VIII. ker.': array{constituencies: array{'Budapest 01.', 'Budapest 06.'}, coordinates: array{lat: 47.4894184, lng: 19.070668}}, ...}, Csongrád-Csanád: array{Algyő: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3329625, lng: 20.207889}}, Ambrózfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3501417, lng: 20.7313995}}, Apátfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.173317, lng: 20.5800472}}, Árpádhalom: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.6158286, lng: 20.547733}}, Ásotthalom: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.1995983, lng: 19.7833756}}, Baks: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.5518708, lng: 20.1064166}}, Balástya: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.4261828, lng: 20.004933}}, Bordány: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.3194213, lng: 19.9227063}}, ...}, Fejér: array{Aba: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 47.0328193, lng: 18.522359}}, Adony: array{constituencies: array{'Fejér 4.'}, coordinates: array{lat: 47.119831, lng: 18.8612469}}, Alap: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.8075763, lng: 18.684028}}, Alcsútdoboz: array{constituencies: array{'Fejér 3.'}, coordinates: array{lat: 47.4277067, lng: 18.6030325}}, Alsószentiván: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.7910573, lng: 18.732161}}, Bakonycsernye: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.321719, lng: 18.0907379}}, Bakonykúti: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.2458464, lng: 18.195769}}, Balinka: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.3135736, lng: 18.1907168}}, ...}, Győr-Moson-Sopron: array{Abda: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.6962149, lng: 17.5445786}}, Acsalag: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.676095, lng: 17.1977771}}, Ágfalva: array{constituencies: array{'Győr-Moson-Sopron 4.'}, coordinates: array{lat: 47.688862, lng: 16.5110233}}, Agyagosszergény: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.608545, lng: 16.9409912}}, Árpás: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5134127, lng: 17.3931579}}, Ásványráró: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.8287695, lng: 17.499195}}, Babót: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5752269, lng: 17.0758604}}, Bágyogszovát: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5866036, lng: 17.3617273}}, ...}, ...}.",
+				"Method Bug8146bError\LocationFixtures::getData() should return array<non-empty-string, array<non-empty-string, array{constituencies: non-empty-list<non-empty-string>, coordinates: array{lat: float, lng: float, ...}}>> but returns array{Bács-Kiskun: array{Ágasegyháza: array{constituencies: array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}, coordinates: array{lat: 46.8386043, lng: 19.4502899}}, Akasztó: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.6898175, lng: 19.205086}}, Apostag: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.8812652, lng: 18.9648478}}, Bácsalmás: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1250396, lng: 19.3357509}}, Bácsbokod: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.1234737, lng: 19.155708}}, Bácsborsód: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.0989373, lng: 19.1566725}}, Bácsszentgyörgy: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 45.9746039, lng: 19.0398066}}, Bácsszőlős: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1352003, lng: 19.4215997}}, ...}, Baranya: non-empty-array<literal-string&non-falsy-string, non-empty-array<literal-string&non-falsy-string, (non-empty-array<literal-string&non-falsy-string, float>)|(non-empty-list<literal-string&non-falsy-string>)>>, Békés: array{Almáskamarás: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4617785, lng: 21.092448}}, Battonya: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.2902462, lng: 21.0199215}}, Békés: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.6704899, lng: 21.0434996}}, Békéscsaba: array{constituencies: array{'Békés 1.'}, coordinates: array{lat: 46.6735939, lng: 21.0877309}}, Békéssámson: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4208677, lng: 20.6176498}}, Békésszentandrás: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.8715996, lng: 20.48336}}, Bélmegyer: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.8726019, lng: 21.1832832}}, Biharugra: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.9691009, lng: 21.5987651}}, ...}, Borsod-Abaúj-Zemplén: non-empty-array<literal-string&non-falsy-string, non-empty-array<literal-string&non-falsy-string, (non-empty-array<literal-string&non-falsy-string, float>)|(non-empty-list<literal-string&non-falsy-string>)>>, Budapest: array{'Budapest I. ker.': array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.4968219, lng: 19.037458}}, 'Budapest II. ker.': array{constituencies: array{'Budapest 03.', 'Budapest 04.'}, coordinates: array{lat: 47.5393329, lng: 18.986934}}, 'Budapest III. ker.': array{constituencies: array{'Budapest 04.', 'Budapest 10.'}, coordinates: array{lat: 47.5671768, lng: 19.0368517}}, 'Budapest IV. ker.': array{constituencies: array{'Budapest 11.', 'Budapest 12.'}, coordinates: array{lat: 47.5648915, lng: 19.0913149}}, 'Budapest V. ker.': array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.5002319, lng: 19.0520181}}, 'Budapest VI. ker.': array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.509863, lng: 19.0625813}}, 'Budapest VII. ker.': array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.5027289, lng: 19.073376}}, 'Budapest VIII. ker.': array{constituencies: array{'Budapest 01.', 'Budapest 06.'}, coordinates: array{lat: 47.4894184, lng: 19.070668}}, ...}, Csongrád-Csanád: array{Algyő: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3329625, lng: 20.207889}}, Ambrózfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3501417, lng: 20.7313995}}, Apátfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.173317, lng: 20.5800472}}, Árpádhalom: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.6158286, lng: 20.547733}}, Ásotthalom: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.1995983, lng: 19.7833756}}, Baks: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.5518708, lng: 20.1064166}}, Balástya: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.4261828, lng: 20.004933}}, Bordány: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.3194213, lng: 19.9227063}}, ...}, Fejér: array{Aba: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 47.0328193, lng: 18.522359}}, Adony: array{constituencies: array{'Fejér 4.'}, coordinates: array{lat: 47.119831, lng: 18.8612469}}, Alap: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.8075763, lng: 18.684028}}, Alcsútdoboz: array{constituencies: array{'Fejér 3.'}, coordinates: array{lat: 47.4277067, lng: 18.6030325}}, Alsószentiván: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.7910573, lng: 18.732161}}, Bakonycsernye: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.321719, lng: 18.0907379}}, Bakonykúti: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.2458464, lng: 18.195769}}, Balinka: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.3135736, lng: 18.1907168}}, ...}, Győr-Moson-Sopron: array{Abda: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.6962149, lng: 17.5445786}}, Acsalag: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.676095, lng: 17.1977771}}, Ágfalva: array{constituencies: array{'Győr-Moson-Sopron 4.'}, coordinates: array{lat: 47.688862, lng: 16.5110233}}, Agyagosszergény: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.608545, lng: 16.9409912}}, Árpás: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5134127, lng: 17.3931579}}, Ásványráró: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.8287695, lng: 17.499195}}, Babót: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5752269, lng: 17.0758604}}, Bágyogszovát: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5866036, lng: 17.3617273}}, ...}, ...}.",
 				12,
 				"• Offset 'constituencies' (non-empty-list<non-empty-string>) does not accept type array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}.\n• Sealed array shape can only accept a constant array. Extra keys are not allowed.",
 			],