Additional meeting and call-related features and issues within Microsoft Teams for business
I have been recently having this problem, at least in my case its due to me disabling the Hands-Free device for my headphones as it causes issues in most other apps and has a much lower bandwidth and therefore quality. It seems teams continues to try and use this device during calls/meetings despite it being disabled. The work around is to disable the Handsfree Telephony from the blue tooth device itself: