Both my wife's and my iPhone 12's have the same issue. Our voice connections are like finger nails on a chalk board. Apple says its on Verizons end but Im thinking the voice connections are on apples end. The mic picks up the background noise of conversations and presents it louder then the person your speaking with. Almost like while on speaker phone but your phone is at the end of a hallway with a few people speaking in between. We've both reinstalled iOS 14.1, per Apple support, and started from scratch with the same results.