iPhone 12 microphone problem ?

Hello.

I have weird problem with my iPhone 12. very often when i call somebody person i call or he calls me, cant hear me or they tells me im „underwater”. First thing comes to my head was microphone is broken or something but.. microphone is working perfect in camera and recorder. Thing is weird because there is a easy way to fix it everytime by changing output from iphone to speaker and back again to iphone, then people can hear me perfect again.

I dont use any Bluetooth accessory and tried reset to factory settings multiple times, nothing helps.

Any ideas? :)