Very weird noise during the call.

Hi guys! I own Iphone 11 Pro Max and in recent days couple people mentioned to me that they can hear very loud static noise in the background while talking over the phone.

Today I did a few tests with my dad and my mate and thats what we have found :

-The noise only apears when Im not talking.

-When I turn on the speaker the noise disapears.

-Voice notes works fine, no cracking noise at all.

-When calling using WhatsApp or Facebook messenger EVERYTHING WORKS FINE and they can hear me without ANY noise.

I did try Varius option like tuning of WiFi, VoLTE, going to 3G only, tuning off WiFi call, switching of and off the phone etc

I did update to IOS 15 today and nothing has changed.

Anyone has any idea? It isn't damaged speaker as like I said this problem not exisiting while using other call apps, ONLY when using proper software.

Thanks!