When I close the lid of my computer, it's quite often that when I open it I don't need to type my password. The network takes some seconds to reconnect, which means that is was suspended. Of course in the settings I said: lock screen on suspend. It however doesn't always happen. => Security issue: so I raise the severity to major. I don't know how to debug further...
next time it happens I'll send the journalctl concerned part..
Are you using logind?
In journalctl I found this: systemd-logind[430]: Lid closed. So I guess yes
Discussion on IRC showed that closing the lid can interact with the touchpad, thus the common and well known problem of input grab disables lock screen happens *** This bug has been marked as a duplicate of bug 78871 ***
Created attachment 96951 [details] dump of the interesting part of journalctl