This issue has plagued Samsung phones for quite some time now and I still have yet to see an official answer on this bug. The problem is this, if I take a photo with HDR set to OFF, the phone camera is still processing it in HDR. I've put a video here to show this annoying problem. Update after update after update, the problem still persists. I had this issue on the S21 Ultra and now on the S21 FE.
I have posted here a video of the problem: