Currently, we show locked modal to the user to prevent them from collaborating in situations where it could lead to data loss.

This would be:

• Plugins using legacy meta-boxes being active
• More than 3 collaborators being active
• A post being more than 1 MB in size
• User being disconnected from the provider due to a network issue

Due to the nature of the JS world, this modal along with the overlay can be deleted via the developer console. This means that changes can be made to the post and be saved by a locked out collaborator. If any other collaborators working on the post save their changes as well, it'll override the changes from the locked out collaborator. Going to the revisions UI will reveal the locked out collaborator's changes, followed by the changes from the other collaborators.

Should we start to enable features like read-only mode, or any other features that require the content to only be edited by known collaborators this'll be a problem.

I've marked this as an enhancement rather than a bug.