Only show active cameras in the quadrant view.
Don't waste quadrant/main screen space with place-holder images of either people with camera off or phone callers. If only one participant turns their camera on (but many are in the call) you see them in 1/4 of the screen and the other 3 quadrants are place-holders. Why not show the active speaker full screen, or split only as needed with other active cameras?
Roger Navarro commented
Missing an active speaker mode for only one active speaker. Skype for Business had this I thought. As does Zoom. Why force the person to Pin one active speaker vs. Teams switching view to one active speaker.