It is transient and fleeting, and it has little to do with melanin. People of Jewish descent, Italians, and even the Irish, used to be considered non-white at various points in the last 100 years in the USA. People whose skin is almost white can still be considered black if, say, one of their grandparents was black. But people whose skin is dark at the end of the summer are nevertheless white as long as it turns pale during winter.

All of these people are "bipoc", supposedly:

- Dark-skinned descendant of American slaves, living in the US

- Dark-skinned recent immigrant to US from Africa, whose parents were important government officials, and one of whose distant ancestors sold slaves to Europeans

- Descendant of Navajo Indians

- Descendant of indigenous Hawaiians

- Descendant of Japanese Hawaiians

- Decendant of Japanese immigrants from turn of 20th century, who were interned in a camp during the war

- Japanese immigrant who moved to US in 2005, for university

- Son of migrant Mexican farmworkers

- Descendant of conquistadores whose parents were top executives in a large Mexican corporation

- Lebanese Muslim immigrant

- Lebanese Christian immigrant

- And so on…

What interesting characteristic do these people all have in common, that "white" people don't also share? Absolutely nothing, other than that they don't tick the "non-Hispanic white" box on stupid USian forms.