Tommy Sotomayor has done several videos on this subject, particularly focusing on violence and cruelty by dark-skinned black females against lighter-skinned classmates or acquaintances.
He talks about how black people have many names for lighter-skinned blacks, and for different degrees of melanin content. Words I've never heard before.
Understand, I think. But in general, crueler to their own even than a lot of white people are.