I'm posting this in General Discussion because there's no discrete topic for X Webcam. There should be because so many people find it problematic!
There are many frustrated people who've been trying to get X Webcam to work on macOS 11.x (Big Sur)
If you check the System Requirements on this page you will see that X Webcam is only supported on macOS versions 10.12 -> 10.15
What I find truly astonishing is that the latest version of X Webcam (v2.1) was released in early 2021 and macOS Big Sur was GA in November 2020.
Why would anyone release a piece of software that patently doesn't work on the current version of any particular operating system?