Since kernel 5.10 shutdown has been spotty, often ending up with a blank screen or with an at (@) symbol and blinking cursor and I have to force power down. Since then it has gotten worse. From about 30% of the time to 80%+ percent of the time it does not work.
Also sleep just causes the system to restart rather than go into sleep mode (prior to 5.10 it worked fine).
I tried adding
acpi=noirq
as few others have suggested and it does seem to allow shutdown to happen (though I only tried it once), but causes the keyboard to stop working (not sure what the connection is).