CSS validation error in the style editor #55271

Description

When editing the custom style for a specific block the CSS editor always display the validation error icon in the bottom right corner.

Step-by-step reproduction instructions

1. Customize the appearance of specific blocks for the whole site.
2. Select the "Heading" block
3. In the advanced panel add a rule like: "color: red;", with or without the ;

Screenshots, screen recording, code snippet

Environment info

• WordPress 6.4-beta3
• Gutenberg 16.7.1

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