Description

Originally reported at https://wordpress.org/support/topic/wordpress-7-0-rc1-classic-theme-stylebook-broken/

props to @cabrailsford @fierevere

My investigation revealed that this issue was caused by #72681.

WP 6.9

WP 7.0 or Gutenberg

Step-by-step reproduction instructions

• Activate Twenty Twenty-One
• Access Appearance > Design > Styles

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

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure