Description

The default mediaWidth setting for the Media & Text block does not change when updated in the theme.json file of a block theme.

Step-by-step reproduction instructions

1. Install or activate a Block theme (e.g., Twenty Twenty-Four or Twenty Twenty-Three).
2. Edit the theme’s theme.json file to set block-level settings for the Media & Text block to change the default mediaWidth.
3. Check the block’s settings in the editor to see if the default mediaWidth has changed.

Expected Result:
The default mediaWidth should update to the new value set in the theme.json file.

Actual Result:
The default mediaWidth remains at 50, even after clearing the cache and switching themes back and forth.

Code Snippet from theme.json:

{
  "settings": {
    "blocks": {
      "core/media-text": {
        "mediaWidth": {
          "type": "number",
          "default": 60
        }
      }
    }
  }
}

Also tested:

"core/media-text": {
        "custom": {
          "mediaWidth": 60
        }
      }

and this:

            "core/media-text": {
        "attributes": {
          "mediaWidth": {
            "type": "number",
            "default": 60
          }
        }
      }

Screenshots, screen recording, code snippet

Environment info

– WordPress 6.6.1
– Tested with no Gutenberg plugin
– Also tested with Gutenberg Version 18.9.0
– Browser: Chrome - Version 127.0.6533.90
– Theme: Twenty Twenty-Four and Twenty Twenty-Three
– macOS

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