Unless I’m presenting or speaking for more than an interjection, I generally turn off the sending of video. There’s little value (IMO) in 320p/720p low bitrate “facial expressions” which are just as often compression artifacts as they are information about emotional state.

Maybe once video calls are routinely 1080p/2160p it will matter more, but 320p (the default for most systems today) at a low bitrate isn’t really doing much. You might as well shut it off unless you’re leading the meeting at that moment.

Contrariwise, when you are speaking/presenting, use an external camera (the one in your laptop/ipad/phone is optimized for thickness and thus the lens sucks) and a good soft key light.