I started a survival world in the newest snapshot and I didn't notice anything weird because I just explored and skipped the nights sleeping, but then I got to a village and called it home. The first night I passed without sleeping no mobs spawned. I have the difficulty set to hard, I tried to change it to peaceful and back to hard and nothing happened. A few mobs spawned, though, I got a raid and that worked well, I found a cave spider spawn and that worked too, also I found a few mobs, but a lot less than I used to find in older versions in a hard difficulty. I don't know if this is something that is meant to be like this. I tried creating another world, set the time to midnight, still being in hard, and only spawned a witch and a skeleton. 

Also in my jungle there were no parrots, I don't know if the spawn zone changed or it is another issue :/