I started a hardcore world (maybe it's worth mentioning that I put  Regenerate health off) in 20w46a. I spawned in a village and everything was fine. I closed the game for a few minutes and when i returned all the villagers were white. As you can see in the picture, some villagers are completely white, others have a 'normal' head. I closed my game one more time to be sure, but when I logged in it was still the same. The chance is very slim that the problem is my pc, but the chance still exist.