I just had this error after upgrading to 10.15.7
After some stress, I fixed it by:
1) opening Screen Time in System Preferences, then adding my browsers, FaceTime, Zoom, etc, to the section "Always Allowed"
2) restarting
3) tested things starting with FaceTime (I figure Apple is going to be the most relaxed about their own software).
The camera and microphone worked as normal in all the apps. I also noticed whereas before in Security & Privacy, the Camera and Microphone sections didn't allow me to add anything, those areas were now behaving as one would expect.