If you load a villager in, in 20w06a and go to 20w07a they will disappear. I tried jumping from 1.15.2 to 20w07a and the villagers where there. it was only going from 20w06a to 20w07a.

to reproduce: 

create a world in 20w06a spawn a villager, exit, load 20w07a and villager is gone