In Cycles, the subsurface scattering shader will switch to a
diffuse shader under a few different conditions to improve performance
and reduce noise.
This commit removes the "switch back to diffuse if the scattering
radius is less than a quarter of a pixel" optimization because in some
scenes, this can result in noticable lines as the shader transitions
between subsurface scattering and diffuse.
Pull Request: https://projects.blender.org/blender/blender/pulls/133245
b9ebd96539