After a decent play session, I was flying back to my base when I realized all of the animals in my pens were no longer there (image with 4 empty pens). Confused I went to check some other mobs around my base, and I found that all of the villagers in my iron farm had disappeared (image with fletchers tables in an iron farm), all of the axolotls and a turtle had disappeared from a lake near my house (image of a lake with a conduit) and all 3 horses (2 skeleton and 1 normal wearing diamond horse armor, and all nametagged) had disappeared from their stable (image of a stable with an enderchest in front). I also noticed that 2 armor stands had also despawned, in image 5 there should be an armor stand in between the 2 wood corners. (Image of a building with wooden corners). Mobs that did not despawn included a bunch of bees in an underground enclosure, villagers in a walled-in village, a tamed cat and a dog, villagers in enclosed cells, and some turtles in an enclosure, although I think one of those had disappeared as well. Needless to say this is a very upsetting bug that should not have happened. It should be noted that for the iron farm villagers case, it is not normally possible to stand against the corner of the box, I had to break blocks to take this picture.