Microphone muffled on outgoing calls

[Motty2012]

Hi all, a few months back I had this mic problem and Samsung had to replace the board with the bottom mic on and charging port. The technician said it was a know fault that this board was corroding. This makes a mockery of the IP water resistance rating. Anyone else had this issue? 

[Paflipper]

I have the same problem with my S21 ( in warranty ) but the technician said it has to do with 5G because my micro was tested okay. But I still have the same problem. I want them to replace the microphone.

[Motty2012]

Is it muffled on 4G? If so he's talking *****.