diff --git a/tests/lib/TestCase.php b/tests/lib/TestCase.php
index 9c1615ab2b22e..e5c999ffc9d1a 100644
--- a/tests/lib/TestCase.php
+++ b/tests/lib/TestCase.php
@@ -337,6 +337,12 @@ public static function tearDownAfterClass(): void {
 		self::tearDownAfterClassCleanStrayHooks();
 		self::tearDownAfterClassCleanStrayLocks();
 
+		// Ensure we start with fresh instances of some classes to reduce side-effects between tests
+		unset(\OC::$server[\OC\Files\AppData\Factory::class]);
+		unset(\OC::$server[\OC\App\AppStore\Fetcher\AppFetcher::class]);
+		unset(\OC::$server[\OC\Installer::class]);
+		unset(\OC::$server[\OC\Updater::class]);
+
 		/** @var SetupManager $setupManager */
 		$setupManager = Server::get(SetupManager::class);
 		$setupManager->tearDown();