1.marking a humanioa npc,use playerskin or custom skin, (in this time,many players used Double_layer skin)
2.let your shader used seus mod or lab pbr
3.look this mess:

This problem will not occur with the skin you provided. They should be a single layer of skin with only one layer.
I guess the reason is that the epic battle renderer itself does not support double skins.

I think, either we can support double skins as soon as possible, or use the Armor Workshop (I have to mention here that I used the Armor Workshop to make Enpc once before, and it was normal at the beginning, but after I restarted game, the Armor Workshop 's data disappears, and the NPC becomes bare again).
Either I have to give up the gorgeous light effects provided by the shader, or I downgrade my art level and make a single-skinned EP NPC.

this all optifine's wrong.sorry to disturb you

but i wanna oneday we can use armor workshop skin with this mod.

and use this shader ,turn it to lab pbr mod or seus pbr mod

ComplementaryShaders_v4.6.zip

i found a shader mix by my friend will use pbr lights and dont causing this problem
IDK why. BUT I really wannna this mod can used Double_layer skin
。
The cause of this problem may not be related to skins, I took a look, and several of your default skins are also double-layered skins, but they are poorly drawn. Reading the skins of the characters that come with the mod directly will not cause any problems with the shaders, but when I directly take out the skins of the characters that come with the module and put them in the external folder, the same skins, custom skins will cause problems. It's weird.