User blog comment:Araxdied/Why Jolyne's birthmark is yellow in Jojo all star battle?/@comment-25041861-20140613092330/@comment-1739368-20140614052547

Indeed.

As Copious said, the colorists seemed to have been trying to go for a more realistic color style, as birthmarks usually appear a reddish color, though I believe these wern't actually done by Araki himself. The game used only official artwork that the author personally colored, which in most cases are the volume covers or pictures from the artbooks.