Description

Noticed while reviewing #70514

In the Featured Image block, four resolutions are available: Thumbnail, Small, Medium, and Full.

Also, immediately after inserting this block, the "Full" resolution will be selected in this dropdown, and the HTML will look like this:

<!-- wp:post-featured-image /-->

Furthermore, if you select a resolution other than full and then select full again, the HTML will look like this:

<!-- wp:post-featured-image {"sizeSlug":"full"} /-->

In the editor UI, "full" is selected in both cases, but this difference in HTML is important for front-end rendering, because the Featured Image block uses the "post-thumbnail" size as a fallback media size:

This means that if your theme defines this media size via the set_post_thumbnail_size() function, the size of the image rendered on the frontend may change.

Step-by-step reproduction instructions

• Activate the Twenty Fourteen theme. This theme defines 1038 x 576 size as the post thumbnail.
• Prepare a large-sized image and upload it to the media.
• Open the post and set the image as the post featured image.
• Insert two Post Featured Image blocks.
• For one of the Post Featured Image blocks, change the Resolution to something other than full, then change it back to full again.
• Your content HTML should look like this:

  <!-- wp:post-featured-image /-->
  <!-- wp:post-featured-image {"sizeSlug":"full"} /-->
  

• Save the post and view the page.
• Note that the two images have different media sizes.

Screenshots, screen recording, code snippet

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