Followup to #43037. When you add "templateLock":"contentOnly" manually to the code of a group block (no UI yet), the pattern becomes content-only locked and flattens nested blocks, for simpler editing:

There's a big "Modify" button in the toolbar, which unlocks the patterns you can edit, delete, move around nested blocks.

• Let's move this button to the ellipsis menu, to reduce its prominence.

An adjacent question/conversation is whether we should rename the button to "Edit", and have it invoke focus mode at the same time. This could use design feedback. CC: @WordPress/gutenberg-design