Zombie Villagers have no arms while using the Programmer Art/Classic Resource Pack

I was using the Programmer Art/Classic Resource Pack in Minecraft Java Edition and saw a Zombie Villager that had no arms and something weird around it's head, so I started spawning Zombie Villagers and it was the same for them, they all had no arms with that weird thing around their heads. I also tested this with the Default Resource Pack, but the Zombie Villagers were fine, so the bug only occurs while using the Programmer Art/Classic Resource Pack.