Description

The Site Styles "Additional CSS" feature has been around for a while and I believe has always been labeled "Additional CSS":

The same screen/field via the Command Palette is called "Open custom CSS":

I'd recommend all of the following:

1. Change command palette to match existing label of "Additional CSS" (keep "custom css" as a synonym for backwards compatibility)
2. Remove "Open" from the label. Isn't that implied?
3. Consistently use or don't use (I vote for "don't use") the paintbrush icon to represent the "Additional CSS" feature in the Site Editor

Step-by-step reproduction instructions

See above

Screenshots, screen recording, code snippet

No response

Environment info

• WordPress 6.9
• Block Theme

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