I was not clear in my OP. The dock remains on my iPad, as expected, but does not appear on the extended display along with the apps on the left side.I don't think the dock is missing, it is clearly on the external display. I can't say if there's also a dock on the iPad that would be hidden in this picture because of the full screen app. Maybe someone who has iPadOS 16 beta could confirm
View attachment 2015313
This worked perfectly for me!I was having this problem across multiple displays—over and under 4k. The solution I found was to go into settings, select the external display, and then change the screen zoom. Usually it was in a zoomed out mode, and by changing it to a more compact zoom I was able to view the dock and additional UX elements on the external display