This is an issue I've had occasionally when trying to delete a plugin in a custom module. In this example, once a filter format filter plugin has been enabled it's impossible to remove. If you disable it and remove the plugin class from the codebase, it still shows up in the "filter.format.full_html.yml" config.
If you try to edit this file to remove the dependency and then do drush cim, you get an error:
Unexpected error during import with operation update for filter.format.basic_html: The "examplefilter" plugin does not exist.
How do you get rid of this dependency if it shows up in the config when disabled and you can't remove it from the config and import the config without getting a fatal error that the plugin is missing?