Memes

Nobody else has mentioned this so I'll step in. There is a concept known as a "pretendian" who is someone that, despite having no roots in the culture, piggybacks on top of it in order to claim that they also suffered.

It's not simply appropriation but it's closer to saying your grandfather died in the Holocaust when he was actually an accountant in Oklahoma during WW2 and never actually even went off to war.

A more modern example would be when George Santos claimed his mother died in 9/11 and it turns out his mother wasn't in New York and died years later.

Piggybacking on a tragedy or a genocide for sympathy points is bad and the meme is making fun of people who do this. Not specifically all white people.