Steps:

1. Create a world. (preferably creative)
2. Obtain a zombified piglin spawn egg from the creative mode interface.
3. Use the spawn egg.
4. Not a piglin.

Expected Results: 

To see the new zombified piglin model.

Observed Results:

Clearly the zombie pigman texture from 1.14... even the behavior is the same.

I will upload a screenshot later when I am playing minecraft, because currently I am doing  my homework.

(I discovered this glitch when I was speedrunning 1.16.201 and all the zombie piglins had no ears, looked, sounded and behaved like the zombie pigmen before the nether update.)