Whatsapp Audio issues with iPhone 12 Pro

I bought my iPhone 12 Pro in Dec 2020 and since then I have been having whatsapp audio issues. If I am on a group audio call on Whatsapp, the people on the other side can't hear me properly. There is a lot of resound. I took it to Apple Store and they couldn't find any hardware issues. They replaced my phone with a new device and also gave me a new sim card in case the issue persists. I still have audio issues and I don't know what else to do.