I know 1.16 beta added java parity of mob picking up item. When zombified piglin equiped the skull, the zombified piglin just like that.

Here are the three steps I did:

1.Find a zombified piglin

2.give the skull to zombified piglin,(pickup item)

3.give the helmet to another zombified piglin

The zombified piglin with helmet worked normaly, but the one equiped with skull has bug (The skull doesn't have a rotation.