Hi everyone,
After playing around with drivers and camera settings for months, a Lenovo Legion support person finally solved this exact same issue for me.
Open a third-party app that uses your camera, like Skype or Zoom (we used Skype). In settings, you'll find an "enable colour" toggle switch. Pressing that magically fixed my camera on all other apps.
For some reason the factory settings for the webcam Lenovo used in my machine and many others (I have a 15" Legion) have it set to black and white only, and there is no "colour enable" option in windows settings or in the windows camera app.
I hope this helps someone! Cheers.
Rob