Choose None, Blur, Studio, Daylight, Ember or Blush in Voice & video, in a Link’s Camera options, or beside Camera in a Kemble Circle room. The picture is changed in your browser before it is sent; the model that finds you is served by Kemble, and nothing is sent anywhere else for it.
Where a background cannot be drawn — a browser that cannot, a device that cannot keep up — your camera stays off and the call says why, rather than showing what you chose to hide.