I think it's just because the next couple of products didn't need public polls: Monsters of the Multiverse and the Critical Role book.
If you look back at the latest couple of years, UA always contained material which would be published just a few months later, so it was perhaps mostly decided but they were still evaluating whether to cut or adjust some of it. We got many UA about stuff ending up in Tasha, then Fizban, Van Richten's, Witchlight, Strixhaven...
But perhaps MotM technical changes were completely decided internally, and the general trends on aligment and races were talked about on other media. Critical Role material is maybe non-negotiable by the community at large.
The Critical Role book is also an adventure and probably doesn't include a lot of new mechanics or abilities that would be UAed.
I think that after Monsters of the Multiverse, the rest of the material for 2022 is likely adventure books and setting books, not a lot of new mechanical crunch.