Horse, skeleton horse, zombie horse, donkey, and mule textures are displayed incorrectly in Steven Universe resource pack

Summary:
The textures of the horse, skeleton horse, zombie horse, donkey, and mule are not displayed correctly in the Steven Universe resource pack.

Steps to Reproduce:

1. Open a world with the Steven Universe resource pack enabled
2. Spawn a horse, skeleton horse, zombie horse, donkey, and mule
3. Observe the textures of these mobs

Observed Results:
The textures appear distorted and partially invisible.

Expected Results:
The textures should display correctly.

Screenshots/Videos:

Video of what these mobs should look like:
https://youtu.be/JKLbDfvSpUA?t=161