That's the OIS - optical image stabilization, it makes the lens move opposite to the motion of the phone to compensate for shaky hands to give you a super steady shot. It always used to rattle, since the S21 Ultra. Chances are, you just haven't held it near your ears and given it a shake before 😊 It's a feature, not a flaw. It's supposed to happen, and happens with all Ultra phones.
