I tried to gamble and see if I could buy a refurbished iPad from Apple that was on a version 14.x but I was not fortunate. Very shortly after unboxing this iPad, I could feel/see the noise in the screen and it started the slow trigger of a headache. I A/B'd it with my good iPad and figured it had to be on a 15.x version. After getting it setup, sure enough, it was on 15.1. It's going back. This is the second iPad I have tried including one of mine that I updated weeks ago (regrets).
It's weird I don't find other posts outside this forum of iOS 15 causing issues with others. It's night and day for me.
I started a thread over on their side. If you have a similar issue, please chime in over here.