MX keys backlight has some issues...
It's turning the backlight off (level 0) for no reason or it turning itself on even if there's nothing moving around it.... EG: https://www.youtube.com/watch?v=gzFVTGEDnGQ

Steps checked:
1. Battery is full
2. There's no light other than the monitor in room
3. Backlight is turned on in Logitech Options. Tested with both Old and new Software.
4. Turned keyboard on / off
5. Disconnect / reconnect usb receiver