Ensure Zoom has access to your device's microphone. Go to Settings > Privacy > Microphone and switch on the toggle for Zoom. Android: Go to Settings > Apps & notifications > App permissions or Permission Manager > Microphone and switch on the toggle for Zoom.
i am also having this problem, nothing helps, the microphone works on other apps like OBS for example but not in the zoom, it seems like the microphone there is looping back audio when i play any audio like youtube video... the only thing that is showing in the mic privacy is "NVM for Windows" with the zoom icon on it when i am using the zoom its showing currently in use