I created a world on the first fully released version of Minecraft, and I, like the semi-idiot I am, decided to convert to the latest 1.16 snapshot. Now the loot tables specific to 1.16 have all been messed up by not generating anything, the ziglins look the same but they have the arms of the old zombie pigman, the lighting is like it was in 1.0.
The seed if you would like to test is -647561876807790335, This is not the world I was talking about but affected the entire snapshot for me.
Loot Table issue is MC-186067, Zombified Piglins look normal to me and so does the lighting - so I'm really not sure what the issue is.