Strange skin rendering

[skycatminepokie]

Describe the issue

My skin seems to render in a strange way. I've noticed this appearance before with other mods (forge 1.8.9, likely Essential or OptiFine causing it), but this is the first time in a long time. Below is how my skin normally renders (and usually renders in-game):

The SkinShuffle preview renders it like this: It also occasionally renders like this in-game, but only with this mod installed. My friends (playing without the mod, server has the mod) haven't seen the bugged rendering on their side before.

Not sure what the edge case is - maybe it's something that I need to fix with my skin, but the skin is very old. I'm fairly certain I'm using the right player model (classic)

Relevant log output

https://mclo.gs/I6zfJ3G

SkinShuffle version

1.0.1+1.20

Extra information

Default configs.