Video with dark face in nice background

That is your camera. Below is a picture of me in my own room. Nevermind the bearded troll, he doesn't charge you to cross the bridge.

It also matters (in the box of options) whether you've got your ZOOM client set to adjust for low light and also, what your actual screen is. If you have, for example, Zoom set to the Dark background, and have it set fullscreen, the camera will reflect from the screen the amount of light than it will from your physical background.