RTC can cause an unsaved change to persist and cause data loss from the original post

[johnbillion]

Description

It appears that an unsaved change can become "sticky" in the editor and prevent a user from being able to edit a post at its currently published state.

When this happens it's not clear how I can return to editing the post at its currently published state, and it's also not clear that a modified version of the post is being edited as opposed to the original.

Step-by-step reproduction instructions

1. Edit a published post
2. Make a change but do not save it
3. Navigate away (dismiss the browser confirmation as necessary)
4. Navigate back to the editor for that post and observe that your change persists

Depending on how quickly you return to the editor you may see your own avatar position at the point where you made a change.

Screenshots, screen recording, code snippet

You can repeat the process and easily end up with several of your own avatars on the editing screen:

Environment info

• WordPress 7.0 beta 4

This can be reproduced on the make.wordpress.org sites too.

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