Description

There seem to be two issues with the "Desktop (50%)" view introduced in #63870:

• The block breadcrumbs is hidden This appears to be the expected behavior, see this comment.
• Doesn't work in non-iframe editor

Step-by-step reproduction instructions

• Open the post editor.
• Click the View button and Select "Desktop (50%)"
• The block breadcrumbs should be hidden.
• Enalbe Custom fields.
• Click the View button and Select "Desktop (50%)"
• Nothing should happen.

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