I've reported this already via the 'Report a problem' feature in my Xbox, but here goes again.
Repro steps:
1. Enable the aforementioned HDMI-CEC feature. Restart the Xbox when prompted
2. Ensure the Xbox controller is connected to the PC via Bluetooth and not to the Xbox. At this point it should appear as connected on the PC, and button inputs (except pressing the Xbox button; more on that later) shouldn't turn the Xbox or TV on
3. Connect to the Xbox via remote play. Button inputs (except pressing the Xbox button; more on that later) shouldn't turn the TV on
4. Press, or press and hold the Xbox button
As a result, the TV turns on, and the Xbox stays on even if you end the Remote Play session. If the TV was already on (eg. someone else was watching something), the input is switched to the Xbox.
This is incredibly disrupting if there's someone using the TV as they get interrupted, defeating the whole purpose of remote play. However, it's even worse when users are traveling: in my experiment, the Xbox stays on even if the remote session ends, which causes the TV to stay on INDEFINITELY, definitely increasing power consumption and reducing the lifespan of both devices unnecessarily, and possibly causing burn-in. This is further worsened by the fact that traveling users won't be able to see that the TV is on until they're back, at which point the damage (Xbox and TV running for several days!) is done
A couple of workarounds:
1. Disable 'Switch TV input using controller' on the HDMI-CEC settings
2. Disconnect the HDMI cable when you're traveling (seriously?)
3. If you have the 'Console turns off other devices' HDMI-CEC feature enabled, end your remote play sessions by press-and-holding the Xbox button, and selecting 'Turn off console' instead of 'Stop streaming'. This will cause the Xbox to turn off, however in my case the TV stays on. Fortunately my TV has a feature where it turns itself off after 10min of no signal on the current HDMI input, but others may not be as lucky
Question: can someone at Microsoft acknowledge this as a bug, and inform us of next steps you're planning to take to fix it?