Solved
Blurrred Background
The background is always slightly blurred, even though the "virtual background" and "blur" functions are turned off. I have tested 5 different cameras. With all of them I have the slightly blurred background.
On the new versions of MacOS, Apple has added a new Video Effects (Change video effects for FaceTime calls on Mac ). Try to turn off the Video Effects mode while using Zoom. The blurred background effect should then be removed.
If this resolves your issue please mark this reply as an accepted solution.