WYSIWYG editor doesn't save when editing wiki

I am using Gitlab 15.11.2 (community edition via Docker).

I try to edit a wiki with the WYSIWYG editor and it just doesn't save. There's no error message, it brings me back to the page and I see that no changes were made.

Saving does work with the standard text-based editor though.

Also, I notice that when making a change in the WYSIWYG editor, and switching to the markdown editor, the changes aren't preserved through to the markdown editor. But if I go in the other direction they are. And they are even saved now when I save from the WYSIWYG editor (after starting editing with the markdown editor). But going in reverse doesn't work (starting with WYSIWYG editor).

Update: Sept 2, 2023

I've upgraded to latest version of Gitlab v16.3.1, and the problem still persists in both Firefox and Brave.

Both browsers show the follow errors whenever a key is pressed while editing in the WYSIWYG editor:

Firefox:

Brave: