When using the mod on version 1.20.1, the game crashes while trying to preview a skin in the skin change menu when used in conjunction with "3D Skin Layers" making skin swapping impossible. I verified this was the issue by turning off that mod and trying to swap skins. The mod worked fine afterward.

I'm fairly certain they used to be compatible, so something must have changed in one of the two mods since to make them incompatible.

Mod in question:
https://modrinth.com/mod/3dskinlayers

Log:
https://mclo.gs/2Ig7HVX

Looks like there may be a pull request to fix the issue, though it might just be for their version of Minecraft.