I think this is a bug. While setting up foliage assets I have noticed problems with the way it was lit. Some of the faces pointing towards the sun are dark/shadowed. And some of the faces on the shadowed side of the asset are bright (even though Subsurface Color is set to zero). I’ve checked my vertex normals and they are correct.
I would expect the faces on the shadow side to all be dark. And the faces on the side facing the sun to be bright/lit.
The first image shows the problems, some leaves/faces are dark, others are bright. The shadowed side looks too bright.
The second image shows a default shader with two sided added. Again the leaves facing the sun are dark, the shadow side too bright. Changing the shading model to Two Sided Foliage does fix some of these issues, but makes the whole asset too bright- see above image.
Last image shows Subsurface Colour set to red. The Subsurface Color is showing on the sun lit side. I would expect to to only show through on the shadowed side. The shadow side has less colour than the lit side!
