**System Information**
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.07
**Blender Version**
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: `rBf1cca3055776`
Worked: (newest version of Blender that worked as expected)
**Short description of error**
When using the Principled GGX transmission the fresnel effect does not decrease with increasing roughness as it should.
**Exact steps for others to reproduce the error**
{F12934718}
In this test file only the specular reflection is visible. The gradient going into the roughness input goes from 0 at the top to 1 at the bottom. As can be seen there the fresnel effect does not otne down with increasing roughness.
Multiscatter GGX does not have this issue.
Apart from that I could not find a single source that documents how fresnel is calculated in the Principled BSDF. If you read this and know that please tell us the source.
Thank you and have a great day!