New install on a SD card with
CoreELEC-Amlogic-ng.arm-21.2-Omega-Odroid_N2.img
Wifi only setting then transfer
CoreELEC-Amlogic-ng.arm-21.1.1-Omega_devel_20241207115537.tar
in .update
No new setting, working fine no screen cut off.
But as soon I restored a recent backup from my usual (official 21.2 and working well) install, the issue came back.
I made a new install again (working fine) and now try to find what setting or add-on is the culprit, adding them one by one.
I’ll let you know.