I applied the Dune suggested fix to delete and reload Netflix, and am able to stream 1080p, but no 4k. I am, however, able to stream in Dolby Atmos, which I am happy about.
In Disney plus, I am able to stream also only in 1080p, but do get either Atmos, or DD Plus.
In both cases, when I first signed in, I got notices from Netflix and Disney Plus that stated a new device had been signed in, and was identified as "Android Tablet".
I recall reading somewhere tah both services only stream 1080p to tablets, so that may be an answer as to why no 4k.