I was messing around with the warden until I saw that the warden kept roaring at the piglin that had angered it and had transformed into a zombified piglin.

This also works for hoglins transforming into zoglins as long as the zoglin doesn't hit the warden.

This only happens when the warden is mad at the piglin/hoglin first, then transforms and continues to roar until it detects the zombified piglin or zoglin.