This has been an issue since the beginning, and not sure if it's a technical one, but the color white has a pinkish tinge in shaded areas when used on most flat "skin" costume pieces as well as skin color. You can't get a solid white. There are some newer pieces where you can get solid white (Witch Bare/Lace, Tattooed Tank Top, Labeaux, etc), so I'm not sure what the issue is, but it's a long-standing one. And it's just the color white. Every other color looks fine as far as I can tell. For other colors the shading is the correct tonality , but for white it's a pinkish tone instead of greyish.
Here you can see that white skin isn't completely white (look at the face and knees)
And here you can see upper and lower female skin pieces also aren't true white, with a number of areas where there is a pinkish tone instead of a grey one.