Dear Maintainer,

*** Reporter, please consider answering these questions, where appropriate ***

   * What led up to the situation?
A laptop running buster only has an HDMI port and that works. Its successor has an USB-C port and runs bullseye. Mate and HDMI do not generate output. bookworm on this laptop only work with HDMI on Gnome or Plasma using Wayland.
   * What exactly did you do (or not do) that was effective (or
     ineffective)?
I tested all of the available UIs under 6.1.0-7-amd64; 6.1.0-5 (this boot) on the same laptop shows the same issues.
Sometimes the monitor shows a desktop using HDMI - but the image is copied from the default screen and will not update. It's a zombie. Sometime the monitor is gray, although the cursor (moved by the mouse) shows and moving the location of the monitor works, so whatever region is saying what +-X, Y-+ locations are valid, is not including the HDMI area.
   * What was the outcome of this action?
Gnome Classic and Plasma give options (Wayland, x11) and HDMI fails on x11.
   * What outcome did you expect instead?
I hooked up two external monitors and x11 should allow all three to work at the same time.
If I add a screen with HDMI, x11 should support it.