Do you see a yield sign in QuickTime Player for your Mac’s FaceTime camera? Here’s the fix
A webcam can be easily misused—and sometimes hijacked by malicious software. While macOS has been generally free of malware that can tap into the camera, and Apple has a hardware-linked green LED that can’t be disabled in software when the camera is active, you may still want to prevent the camera from being used at all.
This typically comes up with kids, but it’s also a tool to disable any app from making use, although macOS will always ask (at least once) before granting access. (There’s a security argument to be made that you can use an account with admin access for setting things up, but in your return use, you use a Standard account, which could even have parental controls enabled for your own focus or safety that you can bypass as needed.)