Do you have any better images?
Is there any indentation at the area of the marks or is it completely smooth?
Have you sliced through one to evaluate the layout of the fibers?
My two thoughts are either it’s a jet mark that’s appearing on certain parts due to the temperature of the tool (may require modification of the cooling design) or an instance where the glass fibers are clumping up due to some resistance inside the mold or the speed of injection and not getting enough material surrounding them (why cutting it into cross sections might be useful).
Has a mold flow analysis been done on the tool?