that has nothing to do with the graphics update.
If you look at the youtube video, the hair has light reflection and looks much better then before (crappy zig zag lines)>
Some cloaks change the hair aspect, if the hair is long so it would not go through the upper part of the cloak, this is a setting.
Show a screenshot of what exactly are you talking about because there are many many hairs, and combinations.
Again, the light of a map, reflections , all influence the color you see, just like in real life. Before it was matt black no matter where u were because the hair was a simple texture color that was not interacting in any way with the world or lights