Laptop starts booting when lid closed after shutdown

This is a strange problem. After installing LEAP 15.1, my laptop starts booting when the lid is closed after a (completed) shutdown on AC power. Googling offers hints about malfunctioning sensors, but it seems this must be a software problem, given the perfect correlation - the problem started exactly after installing LEAP 15.1 and was not present in 42.3.

Any suggestions how to troubleshoot this problem will be much appreciated!

I always disable the laptop lid switch by editing /etc/systemd/logind.conf


Maybe a BIOS setting about this? Is a network cable connected, maybe a WoL event?

Thank you for the suggestion, it seems it helped!

I put this in /etc/systemd/logind.conf


and also disabled all ‘Wake On’ events in BIOS.

For now it appears to be working. Thanks a million!