Old Zombie Pigman model not going back to the Zombified Piglin model after deactivating the Classic Textures resource pack

I know that the Zombie Pigmen got replaced with the Zombified Piglins and how when you use the Classic Textures resource pack they use their old Zombie Pigman model, however when I disabled the Classic Textures resource pack to use the new default textures, the Zombie Pigmen don't return to the Zombified Piglin form. Can you fix this?