Description

In older version of Gutenberg we could replace the "Additional CSS Class(es)" field with our own (with autocomplete for example) by simply using something like:

removeFilter(
    'editor.BlockEdit',
    'core/editor/custom-class-name/with-inspector-control',
)

addFilter(
    'editor.BlockEdit',
    'site/custom-class-name/withInspectorControls',
    withInspectorControls,
)

Now core does not add the core/editor/custom-class-name/with-inspector-control filter, so the removeFilter code above does not remove the custom class name field, so we end up with a duplicate field. This seems to be the commit that changes it: a9cbc06

This affects our Block Class Autocomplete plugin (source) and the more popular EditorsKit plugin (source).

Step-by-step reproduction instructions

1. Install either plugin referenced above
2. Edit page
3. Select a block
4. Open Advanced Inspector panel
5. See duplicate Custom CSS Class(es) field

Screenshots, screen recording, code snippet

Environment info

• WordPress 6.5.2 (bundled Gutenberg version)

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes