Despite the fact that these specific mobs DO allow for separate left and right body part textures, for some reason in the .png file there now are identical textures.
This wasn't an issue with Zombie Pigmen in 1.15.2, back then the separate left/right parts were not identical, but mirrored.
For the Zombified Piglin this results in it having:
identical left and right arms
identical left and right legs
For the Piglin:
identical left and right arms
identical left and right legs
left and right ears do not match
This looks like an oversight when creating the new texture.
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This isn't correctly marked. This isn't as it should be because of how it was with Zombie Pigmen even if this is only partially. Please mark this as open as it is still an issue in the latest versions.

The developers have decided this is intentional after likely having looked at the textures in a lot of detail. This is a bug tracker, not a discussion forum.
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Can confirm in 1.18.1.
Can confirm in 22w03a and is so weird they using same parts, also is confuse when creating textures packs!
Hmmm wait.. not is a duplicate of MC-177265 ? have same description and explanation
Why is this marked working as intended?