OK, thanks for the hint. I just found out that you will only be prompted to update if you:

1. power everything off (shut down deck completely, don’t just sleep it)
2. remove all peripherals connected to the dock (except network cable if you use that for your connection)
3. start the deck
4. if there are any updates for the the dock, they should show in the options of gaming mode

here’s to hoping the updates will allay the display issues