Given #163 was closed over a year ago, this seems like a regression.

Versions:
Minecraft: 1.20.1
Hex Casting: 0.11.1-7-pre-619

Maybe? This texture wasn't doing this in 1.19.2 versions, but I don't know what change exactly caused it.

And ye, I get the general idea of what's going on. The rendering engine can't consistently decide which pixels should be on top since both layers have the same Z value, hence the term "Z-fighting", right? I just don't know anything about item models or how that's fixed so I'm logging an issue.

i'm guessing this happened with the new cad/spellbook skins ?

for future reference this just happens if an item model with multiple texture layers have overlapping outer/exposed pixels in their textures.