They dont actually care about the root issue, which is state-sponsored violence. If George Floyd was white, or if the officer who killed George Floyd was black, nobody would be rioting right now. They only care about George Floyd's race, not the actual abuse of power by police.

Though race is sort of relevant here. Usually black men are seen as "easy prey" by corrupt police officers as they often don't get a fair trial. Police brutality is disproportionately directed against black men for that reason.

Don't get me wrong, police brutality is wrong against anyone, but black men are the most common targets of it. The situation isn't "evil white man against poor black man", but it resonates more with black Americans for obvious reasons. Freedom is for everyone, but sadly at the moment certain people have less freedom than others.