Hmm for me the problems with the S20 Ultra is like Haytch says, the overexposure when using the flash. As for the S21 Ultra, I've only had issues with the camera in certain low light conditions when using the photo mode. Night mode shots are fine. Still though, there's a lot to be improved especially compared to previous Samsung flagships in this regard.
Looking at your image, it looks seriously corrupted. Not seen anything like that on my S21 Ultra.