Got no idea. There doesn't seem to be any settings to account for this. It can't be the camera lens or imaging but must occur post processing. I would raise it with samsung-- they might get you to delete the system cache.-you can do that before you contact them to see if it clears it. Someone on the forum may have an answer. What are your camera settings-- ie. aspect ratio -108mp? Is it happening on main lens or zoom or wide angle or all.
I had the exact same issue with my previous S21 and had it replaced on warranty. Today, the same thing happened with my replacement device. Really frustrating! Seems to be a problem on a totally random basis.
I've had all Galaxy models from S4 up until S10 and for the first time ever I'm really disappointed with Samsung.
I've been having the same problem since I got a brand new S20 5G in July (about 2 months ago). It's really annoying because it's ruined several really nice shots.