Advice from my wife, a photographer:
- if you're still having picture problems (after setting the camera's anti-flicker to 50Hz/60Hz as appropriate), put diffuse illumination on your face e.g. a full-screen browser window on http://blank.org; or for more control--colour temperature as well as brightness--a cheap LED panel and desktop tripod (from a photo supplies shop).
- turn off any "smoothing" or "beauty"features in the cam's software.
- likewise, don't use any fake background features. Pin up a plain bedsheet behind yourself if you think your place is too messy to be the background.
Anyway, once there is a picture of any kind, in my experience most people care more about the audio being unclear or laggy, so you're well ahead.
Ideally you want a camera that does clean HDMI out (no ISO indicators etc), but even that can be worked around if you run OBS studio and crop it out.
In any case, because of all my remote collaboration these days, I bought a decent mike on a boom to use, and my colleagues say it is much better. Still have to find a decent camera.