8 files declare their use of FloodInterface in Drupal 9

BasicAuth.php in core/modules/basic_auth/src/Authentication/Provider/BasicAuth.php

MessageForm.php in core/modules/contact/src/MessageForm.php

UserAuthenticationControllerTest.php in core/modules/user/tests/src/Kernel/Controller/UserAuthenticationControllerTest.php

UserController.php in core/modules/user/src/Controller/UserController.php

UserFloodControl.php in core/modules/user/src/UserFloodControl.php

UserFloodControlInterface.php in core/modules/user/src/UserFloodControlInterface.php

UserLoginFormTest.php in core/modules/user/tests/src/Kernel/Form/UserLoginFormTest.php

UserPasswordForm.php in core/modules/user/src/Form/UserPasswordForm.php