I'm also an it technician with over a decade of experience, and I've seen this first hand, on multiple occasions.

I agree PICNIC is the goto in this scenario; it's not like shutdown commands are new, so why would it not work as intended? it was my initial assumption when faced with these reports; but having seen this occur multiple times, I can confirm it isn't. My running theory is it's KB related, as the issue is intermittent by device (though consistent with an affected device.. as in the device will exhibit this behaviour every time). It's also unique to windows 11.