Unset duotone filters defined in theme.json per block

[ajlende]

Description

It isn't currently possible to unset a duotone filter supplied via theme.json on a block, only override it with a different duotone filter.

I would expect that the 'clear' button resets the filter to whatever was set in the theme.json and there to be another option (a swatch or 'unset' button or something) to disable the filter for that specific image.

See earlier discussion in #34073 (comment)

Step-by-step reproduction instructions

1. Activate a theme with a duotone value applied in theme.json
2. In a post (or the site editor after Fix duotone rendering in site editor #37727 fixes rendering there) try to remove a filter from an image

Screenshots, screen recording, code snippet

No response

Environment info

No response

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