Block specific elements styles are not applied for non-core block plugins

[zpericic]

Description

Block specific styles are not serialized completely if block is not one of core plugins eg. name starting with "core/".

As result global styles are broken and non-core could only be styled one-by-one or via external CSS.

This is regression after #50310.

I have made PR #52228 which shortly address this issue.

Step-by-step reproduction instructions

1. Install custom block which:

   • Name is not starting with 'core/"
   • Supports elements global style (eg. button, link, h[1-6])

2. Apply some global styles on your custom block for button, link or h[1-6].

theme.json example:

{
  "styles": {
    "blocks": {
      "some/block": {
        "color": {
          "background": "black",
          "text": "white"
        },
        "elements": {
          "link": {
            "color": {
              "text": "red"
             }
          }
        }
      }       
    },
    "elements": {
      "color": {
        "background": "white",
        "text": "black"
      },
      "link": {
        "color": {
          "text": "blue"
         }
      }
    }
  }
}

3. Link styles are not applied on frontend eg. links are blue. Block-specific elements styles are not serialized.

Result:

<style id='global-styles-inline-css'>
body{...
.wp-block-some-block{color: white; background-color: black;}
...
</style>

Expected result:

<style id='global-styles-inline-css'>
body{...
.wp-block-some-block{color: white; background-color: black;}
.wp-block-some-block a:where(:not(.wp-element-button)){color: red;}
...
</style>

Screenshots, screen recording, code snippet

No response

Environment info

Versions:

• WordPress: 6.2.2 and newer
• Gutenberg: 16.1.0

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

[zpericic]

This is resolved in Wordpress by 4174 and merged in Trac 56254.

Error still persist if guttenberg is active.

[carolinan]

Are these issues duplicates? https://github.com/WordPress/gutenberg/issues/46454