This morning I did what I’ve never needed to do in the past, I downgraded an iThingy to the previous OS. It was a PITA and it will be a while before everything gets re-downloaded and back to the way they were pre-15. But worth the effort. I’m lucky in that I also have an iPad mini 5 which I kept nearly identical to my iPad Air 2020, and I had left the iPad mini 5 on iPadOS 14.8, so I was able to Restore from an iCloud Backup from the iPad mini 5. Unfortunately the iPad Air 2020 had already automatically created two backups after it was using iPadOS 15, so restoring from those would have meant going right back to iPadOS 15. I know this because I tried and had to restart the iPad setup routine, then selected to restore from an iPad mini 5 recent iCloud backup. If I had already updated the iPad mini 5 to iPadOS 15, I would have had to reinstall everything from scratch. So dodged a huge bullet there.
Immediately after the downgrade/restore I turned Updates to OFF. No more of those, at least until/if Apple listens to the complaints and fixes a lot of crap they put into iPadOS 15.
At any rate, the whole process went fairly smooth and only took about an hour, at most. It will take a bit longer to get everything rearranged and to download all the apps and data from iCloud. Worth the effort though.
I want to reiterate that I’m only upset with iPadOS 15. It is a buggy, crappy mess. iOS 15 seems perfectly okay on my iPhone XR and I’m happy with it. tvOS 15 seems perfectly fine on my ATV 4K 2017 and I’m happy with it. Those are the only other 15 level OSes I have installed.