12 files declare their use of RequestMatcherInterface in Zircon Profile 8

AccessAwareRouterInterface.php in core/lib/Drupal/Core/Routing/AccessAwareRouterInterface.php

Contains \Drupal\Core\Routing\AccessAwareRouterInterface.

ChainRouter.php in vendor/symfony-cmf/routing/ChainRouter.php

ChainRouterInterface.php in vendor/symfony-cmf/routing/ChainRouterInterface.php

ChainRouterTest.php in vendor/symfony-cmf/routing/Tests/Routing/ChainRouterTest.php

ConfigTranslationController.php in core/modules/config_translation/src/Controller/ConfigTranslationController.php

Contains \Drupal\config_translation\Controller\ConfigTranslationController.

DynamicRouter.php in vendor/symfony-cmf/routing/DynamicRouter.php

MockMatcher.php in core/modules/system/src/Tests/Routing/MockMatcher.php

Contains \Drupal\system\Tests\Routing\MockMatcher.

NestedMatcher.php in vendor/symfony-cmf/routing/NestedMatcher/NestedMatcher.php

PathBasedBreadcrumbBuilder.php in core/modules/system/src/PathBasedBreadcrumbBuilder.php

Contains \Drupal\system\PathBasedBreadcrumbBuilder.

Router.php in vendor/symfony/routing/Router.php

RouterListener.php in vendor/symfony/http-kernel/EventListener/RouterListener.php

TestRouterInterface.php in core/tests/Drupal/Tests/Core/Routing/TestRouterInterface.php

Contains \Drupal\Tests\Core\Routing\TestRouterInterface.