Comment 9 for bug 1929209

No one else has joined this bug, but it has continued to make life with my expensive monitor extremely annoying.

And despite suggestions above, I am certain this is not a hardware problem.

Here is new proof:
 yesterday, I initiated an upgrade (do-release-upgrade) to 22.04 from 21.10 from the command line.
By chance, I tried full-screening a video while the upgrade was in progress. Amazingly, it worked flawlessly the entire duration of the upgrade! ! !
 As soon as it was done and rebooted, I tried playing that video again and it did the black-screen / device searching every 3 seconds or so, as it always has.

So, how can I reproduce the thing that the upgrade did?! It said something at the beginning about disabling screen lock or something like that, but I have tried turning off all such things in my settings already.