Z-Fighting is present on the legs of the entities who have different colors next to each other,. As I could see, this ocurrs on piglins, his variants, any other mobs with boots and the player. This doesn't happens on zombies, for example, because both legs have a symmetric texture. Although the z-fighting it's stil ocurring, it doesn't show up because of what I mentioned.

Note: This bug is the same as MC-203299, I just added the screenshots with the debug screen enabled (My apologies for not doing that the first time).  I also saw that when any mobs wears boots, it causes z-fighting on them too.