Unable to change the cover block overlay/background colours

Problem/Motivation

When using the latest version of 3.0.x, it seems that you can no longer change the overlay colour for existing Cover blocks.

It only lets you change the text colour. This issue might apply to other custom blocks or related to certain implementation WordPress hooks.

On testing on a wordpress installation running 16.7.0, the Layout panel is also meant to provide an "Inner blocks use content width" checkbox, but that's also missing.

Steps to reproduce

Create a cover block with a specific colour. You no longer have the option to change the colour from the UI.

Proposed resolution

Ensure feature parity with the WordPress version or attempt to update to the latest version of Gutenberg since the current version appears to be based off an old release candidate (16.7.0-rc1).

Remaining tasks

Investigate and provide a fix for the issue.

User interface changes

The overlay colour should be available as an option for cover blocks.

API changes

N/A