>>149309677 (OP)Why do people keep asking this when the show very clearly and unsubtly spells it out? Mina was a racist who was using magic (her "privilege" as a mewman) to genocide all the monsters of Mewni. Star's solution is to destroy this institution of "privilege" so that Mina can't use it to genocide anymore.
It was a dumb ending because they wrote themselves into a corner with the whole monsters being minorities thing. Mina was a literal joke character who was shoehorned into being the final villain because her gag was that she was crazy and racist against monsters, and they needed someone to represent the racist side.