diff --git a/src/Testing/PHPStanTestCase.php b/src/Testing/PHPStanTestCase.php
index 03b2e4335c7..f70ec82fcff 100644
--- a/src/Testing/PHPStanTestCase.php
+++ b/src/Testing/PHPStanTestCase.php
@@ -2,6 +2,7 @@
 
 namespace PHPStan\Testing;
 
+use Override;
 use PHPStan\Analyser\ConstantResolver;
 use PHPStan\Analyser\DirectInternalScopeFactoryFactory;
 use PHPStan\Analyser\Error;
@@ -40,6 +41,24 @@ abstract class PHPStanTestCase extends TestCase
 
 	use PHPStanTestCaseTrait;
 
+	/**
+	 * Re-register the runtime container as the global static reflection provider before
+	 * every test. Enable this in tests that construct Type objects directly and assert
+	 * PHP-version-dependent reflection results, so a foreign PhpVersion leaked by another
+	 * test can't flake them. See https://github.com/phpstan/phpstan/issues/14860
+	 */
+	protected bool $reinitializeContainerBeforeEachTest = false;
+
+	#[Override]
+	protected function setUp(): void
+	{
+		if (!$this->reinitializeContainerBeforeEachTest) {
+			return;
+		}
+
+		self::getContainer();
+	}
+
 	public static function getParser(): Parser
 	{
 		/** @var Parser $parser */
diff --git a/tests/PHPStan/Analyser/AnalyserTraitsIntegrationTest.php b/tests/PHPStan/Analyser/AnalyserTraitsIntegrationTest.php
index 4680f7fccb2..eb5fbc4d67a 100644
--- a/tests/PHPStan/Analyser/AnalyserTraitsIntegrationTest.php
+++ b/tests/PHPStan/Analyser/AnalyserTraitsIntegrationTest.php
@@ -22,6 +22,7 @@ class AnalyserTraitsIntegrationTest extends PHPStanTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		$this->fileHelper = self::getContainer()->getByType(FileHelper::class);
 	}
 
diff --git a/tests/PHPStan/Analyser/TypeSpecifierTest.php b/tests/PHPStan/Analyser/TypeSpecifierTest.php
index aa66c940016..faeacb2f9fc 100644
--- a/tests/PHPStan/Analyser/TypeSpecifierTest.php
+++ b/tests/PHPStan/Analyser/TypeSpecifierTest.php
@@ -61,6 +61,7 @@ class TypeSpecifierTest extends PHPStanTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		$reflectionProvider = self::createReflectionProvider();
 		$this->printer = new Printer();
 		$this->typeSpecifier = self::getContainer()->getService('typeSpecifier');
diff --git a/tests/PHPStan/Command/ErrorFormatter/RawErrorFormatterTest.php b/tests/PHPStan/Command/ErrorFormatter/RawErrorFormatterTest.php
index cf0c0711631..72718f0a28a 100644
--- a/tests/PHPStan/Command/ErrorFormatter/RawErrorFormatterTest.php
+++ b/tests/PHPStan/Command/ErrorFormatter/RawErrorFormatterTest.php
@@ -19,6 +19,7 @@ class RawErrorFormatterTest extends ErrorFormatterTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		foreach (AgentDetector::ENV_VARS as $var) {
 			$this->originalEnvVars[$var] = getenv($var);
 			putenv($var);
diff --git a/tests/PHPStan/Command/ErrorFormatter/TableErrorFormatterTest.php b/tests/PHPStan/Command/ErrorFormatter/TableErrorFormatterTest.php
index 2ec0679fabd..8396630f7c6 100644
--- a/tests/PHPStan/Command/ErrorFormatter/TableErrorFormatterTest.php
+++ b/tests/PHPStan/Command/ErrorFormatter/TableErrorFormatterTest.php
@@ -23,6 +23,7 @@ class TableErrorFormatterTest extends ErrorFormatterTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		putenv('GITHUB_ACTIONS');
 
 		$this->terminalEmulator = getenv('TERMINAL_EMULATOR');
diff --git a/tests/PHPStan/PhpDoc/DefaultStubFilesProviderTest.php b/tests/PHPStan/PhpDoc/DefaultStubFilesProviderTest.php
index a1e0faf4a2a..eef6033cfdd 100644
--- a/tests/PHPStan/PhpDoc/DefaultStubFilesProviderTest.php
+++ b/tests/PHPStan/PhpDoc/DefaultStubFilesProviderTest.php
@@ -17,6 +17,7 @@ class DefaultStubFilesProviderTest extends PHPStanTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		$this->currentWorkingDirectory = $this->getContainer()->getParameter('currentWorkingDirectory');
 	}
 
diff --git a/tests/PHPStan/Rules/Functions/PrintfHelperTest.php b/tests/PHPStan/Rules/Functions/PrintfHelperTest.php
index c8175508082..c2dae58ec4e 100644
--- a/tests/PHPStan/Rules/Functions/PrintfHelperTest.php
+++ b/tests/PHPStan/Rules/Functions/PrintfHelperTest.php
@@ -15,6 +15,7 @@ class PrintfHelperTest extends PHPStanTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		$this->printf = new PrintfHelper(new PhpVersion(PHP_VERSION_ID));
 	}
 
diff --git a/tests/PHPStan/Type/Accessory/HasPropertyTypeTest.php b/tests/PHPStan/Type/Accessory/HasPropertyTypeTest.php
index 8219bc5eab3..5771e7d52da 100644
--- a/tests/PHPStan/Type/Accessory/HasPropertyTypeTest.php
+++ b/tests/PHPStan/Type/Accessory/HasPropertyTypeTest.php
@@ -23,6 +23,11 @@
 class HasPropertyTypeTest extends PHPStanTestCase
 {
 
+	// Pin the runtime container so a foreign PhpVersion leaked by another test
+	// can't flake the version-dependent Closure data set below.
+	// See https://github.com/phpstan/phpstan/issues/14860
+	protected bool $reinitializeContainerBeforeEachTest = true;
+
 	public static function dataIsSuperTypeOf(): array
 	{
 		return [
diff --git a/tests/PHPStan/Type/Generic/GenericObjectTypeTest.php b/tests/PHPStan/Type/Generic/GenericObjectTypeTest.php
index 2f3733c363b..7564cbe9f33 100644
--- a/tests/PHPStan/Type/Generic/GenericObjectTypeTest.php
+++ b/tests/PHPStan/Type/Generic/GenericObjectTypeTest.php
@@ -32,6 +32,11 @@
 class GenericObjectTypeTest extends PHPStanTestCase
 {
 
+	// Pin the runtime container so a foreign PhpVersion leaked by another test
+	// can't flake the version-dependent data sets (reflected variance of built-in
+	// generics). See https://github.com/phpstan/phpstan/issues/14860
+	protected bool $reinitializeContainerBeforeEachTest = true;
+
 	public static function dataIsSuperTypeOf(): array
 	{
 		return [
diff --git a/tests/PHPStan/Type/ObjectTypeTest.php b/tests/PHPStan/Type/ObjectTypeTest.php
index 3a0344983ba..c9a9688c215 100644
--- a/tests/PHPStan/Type/ObjectTypeTest.php
+++ b/tests/PHPStan/Type/ObjectTypeTest.php
@@ -51,6 +51,11 @@
 class ObjectTypeTest extends PHPStanTestCase
 {
 
+	// Pin the runtime container so a foreign PhpVersion leaked by another test
+	// can't flake the version-dependent Closure data sets (dynamic-property
+	// handling). See https://github.com/phpstan/phpstan/issues/14860
+	protected bool $reinitializeContainerBeforeEachTest = true;
+
 	public static function dataIsIterable(): array
 	{
 		return [
diff --git a/tests/PHPStan/Type/Php/GmpOperatorTypeSpecifyingExtensionTest.php b/tests/PHPStan/Type/Php/GmpOperatorTypeSpecifyingExtensionTest.php
index 97c50184e0f..9e8aee6d8b2 100644
--- a/tests/PHPStan/Type/Php/GmpOperatorTypeSpecifyingExtensionTest.php
+++ b/tests/PHPStan/Type/Php/GmpOperatorTypeSpecifyingExtensionTest.php
@@ -24,6 +24,7 @@ class GmpOperatorTypeSpecifyingExtensionTest extends PHPStanTestCase
 	#[Override]
 	protected function setUp(): void
 	{
+		parent::setUp();
 		$this->extension = new GmpOperatorTypeSpecifyingExtension();
 	}
 
diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index 996beeeed75..c5499d47447 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -73,6 +73,11 @@
 class TypeCombinatorTest extends PHPStanTestCase
 {
 
+	// Pin the runtime container so a foreign PhpVersion leaked by another test
+	// can't flake the version-dependent data sets (dynamic-property handling of
+	// final classes). See https://github.com/phpstan/phpstan/issues/14860
+	protected bool $reinitializeContainerBeforeEachTest = true;
+
 	public static function dataAddNull(): array
 	{
 		return [