iPhone 13 Pro Max left-bottom microphone issue.

Hi I have iPhone 13 Pro Max and whenever I have a call (whatsapp, viber, teams etc.) and it is just audio call then everything is good, but when I switch to loud speaker / hands free / video, then the others are barely hearing what I'm saying.

I have called another phone next to me to test the microphones, and it seems that when I activate the hands-free / video option the bottom-left microphone is activated and it makes a problem, while when I switch back to just audio call everything gets back to normal.

When I get too close to the phone, then others can hear me good, but then I can't do Video call (they can see my nose only).

*The phone is clean of any debris, as well protective case was removed during the test - same outcome.

My question is: Is this something that is caused by the software or I need to go to change the microphone?

I have iOS 18.3.1 installed, but the issue persisted with older versions of iOS as well.