6 files declare their use of ConfigurableFormEnhancerBase in Flexiform 8

MultipleEntityForm.php in src/Plugin/FormEnhancer/MultipleEntityForm.php

PageExposure.php in src/Plugin/FormEnhancer/PageExposure.php

SubmitButtonAjax.php in src/Plugin/FormEnhancer/SubmitButtonAjax.php

SubmitButtonLabel.php in src/Plugin/FormEnhancer/SubmitButtonLabel.php

SubmitButtonRedirect.php in src/Plugin/FormEnhancer/SubmitButtonRedirect.php

SubmitButtonRules.php in contrib/rules/src/Plugin/FormEnhancer/SubmitButtonRules.php