Now desktop Guests can turn off their camera while they are in the Green Room. 

Desktop Guest Directors and other guests who may not be joining as presenters can turn off their cameras so they aren’t a distraction during a recording, and Guest Presenters can take a moment of privacy in the Green Room before the broadcast starts. 

Note: Turning off the camera is not recommended for Presenters during a live broadcast. A guest with their camera off will appear as a black feed in the broadcast.

For more information, see this article on Navigating the Green Room