I have a similar issue.
Setup:
* Rpi4 connected directly to the receiver (via HDMI)
* Receiver: Yamaha RX-V675 connected to TV (via HDMI)
* TV: Sony KD55XH9005 (ARC HDMI port)
* CEC is enabled on all devices.
* LE version 11.1, controlled through Yatse (Android)
This setup has been working great until somewhere during the LE v10.x release. CEC started to behave erratically: randomly turning on the TV and receiver at night.
This issue was fixed with one of the last LE v10.x versions and appears to be ok with version 11.0.
With v11.1 the same issues did come up again (occasionally turned on the TV+Receiver overnight), but a few times a week, the RPI just keeps on turning on the connected CEC devices. I have to shut down the Pi to be able to turn off the receiver and tv. Other CEC functionality seems to be ok. I have checked and rechecked the CEC settings, no strange settings were found.
I will enable debug logging and hope i will be able to record the issue.