iPhone 7 microphone not working properly on non Apple apps

Hi,

I'm using an iPhone 7 and, after I updated it to iOS 14, its microphone stopped working properly on non Apple apps (WhatsApp, Instagram, Messenger, etc).

I say "not working properly" because the issue is not that it doesn't record any sound. Actually, it does, but in a very low volume and with a heavy muffled wheezing, just like a really bad, broken microphone.

Yet, this is not a hardware problem since I can record with perfect sound with the iPhone camera and when I use the telephone it works perfectly as well.

Does anybody have a solution for this? It's very frustrating since I use voice memos a lot on these apps.

I ran through a lot of other people complaining about the same thing from posts dating back to 2013 until today, but never a solution. The only person that seem to have find a solution, in 2014, did it through accessing a section that doesn't seem to exist on this last version of iOS ("Restrictions").

Any help would be much appreciated.

Thanks.