The Problem:

I was doing a resource pack, editing the texture of the piglins, and when I started testing it, I realized that it uses only the upper left part of the texture, not the entire file.
I only tried the Zombified Piglins, but I also associated it with problems of the piglin model and its corresponding texture file.

To see the bug:

1.- Download zombified_piglin-piglin_bug.zip

2.- Place in "resourcepacks" folder.

3.-Open the game in the last version (20w09a) in a world.