This seems new since the updates I installed last week. Has happened six times in the last five days, totally repeatable.
Today I was able to resume control without rebooting.
I ssh into my 22.04 box that was unresponsive to keyboard and mouse. I first tried killing all the Chromium and Chrome instances but that didn't work. Then I did "top" and saw "marco" using massive amounts of CPU so I killed it and the system came back to life, Chrome and Chromium came back when I restarted them and resumed where I'd left off, Chrome automatically, Chromium after I did "restore pages".
This is a distressing problem to all of a sudden have on a Linux system. This may be unfounded, but as a Ubuntu user since 2006 it seems to be the more that Ubuntu gets in bed with Microsoft for the "Linux on Windows" offering the more Microsoft-like crashes and lockups I'm seeing on Ubuntu.