Yeah, same issue with the priestess game. Its probably from me but its definetly has to do with the engine.
I know about this one, I've received a previous report of the game doing that. It's strange that it's always the side menu that gets affected. Unfortunately I am at a complete loss as to why this happens and cannot reproduce the issue on my own computer to fix it. Games made in Godot just aren't fully consistent in performance across all platforms and machines running them. Godot is growing rather quickly, so I hope that this gets addressed in a future release of the engine.