@EddieL [MSFT],
Got the problem again today 1/20/2021 with build 21292.1010.
The Xbox bar opened on its own and the PC became unresponsive.
Had to force a restart to get out of the stuck condition.
After the restart everything seemed to be back to normal.
Had this issue once before but then it did no happened again for a few days till this morning.
Fix should be coming soon.
-Eddie