iPad Air 2 brightness issue

i have an iPad Air 2. Night shift is set to off. The problem is that it acts as though it’s not. It keeps readjusting the brightness. I thought maybe it was a hardware problem but the slider moves as it gets darker and lighter.

I saw that someone else asked this question three years ago and the answer was to back it up and put it back to factory settings, then restore. That didn’t fix the problem.

is there another setting for this? Thanks.