(I realize this is a frought topic, so please hold the race science bullcrap replies or the over-reactions in the other direction. I am not a believer in hard biological determinism or "race science," but I also don't dismiss the existence of variations. As with everything else in population genetics and biology, any variations that do exist probably have more than one cause.)
If there's any truth to this, it might be further compounded as people with darker skin spend more time indoors in the modern world. If you have darker skin you need, as far as I know, more sun to make vitamin D, which normally is not a problem if you're outdoors near the equator. Maybe darker skinned people need to be taking more D supplements.
And even clothing.
I don’t think clothing is that big a factor because all humans in hot environments adapt and very little survives in the archaeological record. Many populations lived in heavily forested jungles where they was little sun exposure and those in deserts used stuff like Otjize for sun protection. Given all the ethnographic reporting from the age of exploration, tons of that clothing was probably made of feathers, cordage, bark, and other materials we wouldn’t even think of using for clothing.