Minecraft wiki entry for Zombified_Piglin, associated text: The pre-Texture Update zombie pigman texture file has "THX XAPHOBIA" written on the unused section as a credit by Notch to the skin's original creator.
Deaths of hostile zombified piglins always register as kills by the player they are targeting, regardless of whether that player ever touched that zombified piglin.[8]‌[Java Edition only]
The zombified piglin's angry sound is played twice the speed of the original sound file in the game.‌[JE only]
Applying the Classic Texture Pack changes the zombified piglin's model and texture back to a zombie pigman.‌[Bedrock Edition only]
Baby zombified piglins can be jockeys upon chickens and striders. Uniquely on more than one mob (other than the player).
There is a glitch where the zombified piglin texture appears as the zombie pigman even without the Classic Texture Pack.‌[Bedrock Edition only]