6 files declare their use of KeyValueMemoryFactory in Drupal 9

CronTest.php in core/tests/Drupal/Tests/Core/CronTest.php

MatcherDumperTest.php in core/tests/Drupal/KernelTests/Core/Routing/MatcherDumperTest.php

ProviderRepositoryTest.php in core/modules/media/tests/src/Unit/ProviderRepositoryTest.php

RendererBubblingTest.php in core/tests/Drupal/Tests/Core/Render/RendererBubblingTest.php

Contains \Drupal\Tests\Core\Render\RendererBubblingTest.

RouteProviderTest.php in core/tests/Drupal/KernelTests/Core/Routing/RouteProviderTest.php

Contains \Drupal\KernelTests\Core\Routing\RouteProviderTest.

ThemeExtensionListTest.php in core/tests/Drupal/Tests/Core/Extension/ThemeExtensionListTest.php