For starters, the void isn't really a cave and wouldn't effect her hair color. For the void to change her hair color, hair color is based almost entirely off of melanin which means for her hair to change color it would equally change her skin's color, which makes sense since it isn't just her hair being exposed to the void.
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I'm just trying to figure out where she found all the product to make it look nice. The Void must have some killer salons.
With the KDA skin, she isn't actively in the void at the time, so it fair to see she just dyed it, which also explains why her hair looks nice. It's fairly easy to notice that they are in-fact not performing in the void, so why would she need to wash her hair in the void????