Summary:
When the skeleton horse does not move between the trunk and forelegs, z-fighting occurs.

Steps to reproduce:

1. Summon skeleton horse.
2. Consider where the front legs and torso are attached.

Observed results:
Noticeable z-fighting occurs between the legs and trunk.

Expected results:
Noticeable z-fighting between textures should not be in game.

Video:
Minecraft 2021-11-27 16-38-39.mp4