Apple TV keeps going to sleep on its own after tvOS 18 update

ATV logs actually shown

PineBoard: Attempting to sleep the display

powerd: Sleep revert state: 1

..without user input

apparently HDMI 2.1 cable also not helping for long, I did check sleep setting, timer, disable HDMI-CEC on both ATV and TV, even restart and unplug power cable from ATV and TV not helping

but after spending almost the whole day to narrow down the issue, the workaround was switch to another source input on the TV, and back to Apple TV.. according to ChatGPT:

• After the TV or Apple TV is idle for a while, the LG CX port drops or degrades its HDMI link, even without turning off.
• This causes the Apple TV to misinterpret the display as gone or inactive, triggering internal sleep (powerd, PineBoard, etc.)

Switching Inputs Forces HDMI Renegotiation

• When you switch to another input (e.g., HDMI 2 → HDMI 3) and back, the LG reinitializes the HDMI port:
  • EDID is re-read
  • HDCP/CEC links reset
• Apple TV then sees a "fresh" valid display, keeping it awake.
• Restarting or powering on the TV doesn’t always trigger a full HDMI renegotiation, and why switching inputs works better in your case