Modify the HairShading function in HairBsdf.ush and change the following code:
const float Backlit = min(InBacklit, HairTransmittance.bUseBacklit ? GBuffer.CustomData.z : 1);
to:
const float Backlit = min(InBacklit, GBuffer.CustomData.z);
View details at https://zhuanlan.zhihu.com/p/674637556