Poor qualit of incoming calls.

Hello,

I have a problem with my Iphone XS Max 256GB. Bought it 2 weeks ago. During incoming calls the quality of the voice is very poor. At the beginning I thought it was a problem with a reception in the area where I usually take my calls. Even tried to convince people that must be something wrong with a signal on their side. Then after testing it in different locations, receiving calls from different carriers I realised that I have a poor quality of calls everywhere! The volume of the voice is going constantly up and down. It sounds like taking a call in the basement without a signal. After browsing the internet I found many people have the same problem. Is there any fix for this problem? I’m sure Apple is aware of that. Why they still selling this faulty mobile phone?