There’s been more than a few times, many more, that for whatever reason, Spectralayers loses window focus, or doesn’t take focus when expecting it is, hit ctrl-z and it undoes the ARA2 event and all of a sudden your entire edit history is gone, etc.
This is maybe more of a Cubase request, but there should be a preference to ask the user if they actually want to undo an ARA2 event.