When generating new worlds, villages are primarily spawning with Blacksmith, Butcher, Librarian and Priest type villagers, and not farmer types. I have been randomly generating new worlds with random seeds in creative mode since I noticed the issue. I will randomly generate a world in creative mode (survival is also affected, but it's easier to find villages in creative) and simply hunt down villages. In a dozen worlds or so I've found several villages in each and in all of the villages found thus far I have come across a grand total of two farmer-type villagers.

I've also noticed that some of these villages will also have an oddly high number of Nitwit villagers. Perhaps it is spawning Nitwits instead of farmer types and vice-versa?

I noticed the issue during survival single-play, where I searched for and found a half dozen villages and only a single farmer-type, a Sheperd (but one village had four or five Nitwits). This also seems to affect breeding, as I have not yet managed to breed a single farmer-type villagers, though I have bred several nitwits.