My MacBook camera show me not connected

See if you can try the following 2 things as part of basic troubleshooting first-

1. Reset SMC by following the directions applicable to your MacBook Air here ➔ How to Reset SMC. If that does not solve things then-
2. Reset NVRAM/PRAM by following the directions applicable to your MacBook Air here ➔ How to Reset NVRAM/PRAM. 

Axel F.

Alex F is right and try these first but if this doesn't work, before you start going through too many steps, you might like to check out this discussion: htthttps://discussions.apple.com/thread/251186757?answerId=252724128022#252724128022

It's not pretty I'm afraid - something in Catalina / video conferencing software has gone haywire - not only built-in cameras but USB as well.

Apple knows about the issue and the 10.15.5 update included " Resolves an issue where the built-in camera may not be detected when trying to use it after using a video conferencing app" but so far, people with the problem still have the same problem.

Good luck