I don’t know if it’s justified to claim, as the headline does, that these white Instagram influencers are “pretending to be black.” Only one is doing that – and she only did it for a while. The others are upfront about their ethnic heritage.
On the other hand, cultural appropriation is a thing. I view it as economic: Elvis Presley gets rich doing covers of “race records,” while the original performers struggle to make a living. I think the mainstream definition of cultural appropriation is more broad and intangible than the one I use.