From the 1.16.0.51 beta changelog:
Piglins that somehow end up in the overworld become zombified fairly quickly
Note that the changelog only mentions piglins becoming zombified piglins in the overworld.
However piglins are able to become zombified piglins in The End. Could be intentional due to MC-172107 being reopened.
Observed Results
Piglins shakes and transforms into zombified piglins in The End.
Expected Results
Piglins stays as piglins in The End. (MC-172107)
Thank you for your report!
However, this issue has been closed as Working as Intended.
This will be tracked as a Java Edition issue at MC-172107.
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