I didn’t want to post this last time around (12.0.5->13.0) in case it was a fluke, but after 12.0.5 to 13.0.0 and now on to 13.0.1 I dare say: the updater works quite well for me now. I did not run into any problems, everything worked as intended, nothing needed to be restored or reactivated manually. Very nice!
Thanks for everyone involved. This goes along way towards evergreen Nextclouds everywhere!