iPhone 11 Pro Max microphone issues with Otterbox cover

I have a new 11 Pro Max and when I am using FaceTime people say I’m breaking up bad and they can’t understand me. When I take the cover off that problem goes away. The reason I still thinks a phone issue is that my don has the same phone with the same cover and he has never had this issue. Can someone help me figure out why my phone doesn’t work with a cover on it. I have tried a couple different covers and same issue no matter the cover.