Okay so I got some Dcst hair theories. Hear me out on this one.
So Senku is likely albino right? Red eyes, pale ass skin, white hair, you know him. The green tips defy science but we already knew that (I would say they're dyed but I feel like that's not something he'd do) but anyways.
I think Gen has naturally half black half white like that one condition that I can't remember the name of. But he had to dye the white black for the stage but also didn't want it to be permanent so he just used that stuff that just goes on top. Also because he would need to do it often to hide his roots right.
That black hair dye would degrade over time off his statue which is why his hair appeared to turn white, while real hair dye would stay through petrification because it goes into your actual hair. Hence why Luna's hair stayed pink.
Thank you for listening to me rant about my theories. Well technically read. Idk