They’re not even using it right! The tu quoque fallacy is when you discredit a logical argument based on the opponent’s hypocrisy. Stuff like “you say smoking is bad, but you smoke, therefore you’re wrong and it’s not bad”. It’s a fallacy because your opponent being a hypocrite doesn’t mean their conclusion is incorrect. But when people do “whataboutism” they’re not implying Russia, China, Venezuela, etc. haven’t done anything wrong, they’re criticizing an unjustified double standard that lets the US and its allies act like a moral authority on human rights while getting away with similar or even worse violations.
There are genuine cases when you could call out “whataboutism”, like when an Axis sympathizer tries to bring up muh Dresden and muh rape of Berlin. Because in that case, the person is trying to draw a false equivalence between the side that started a war of extermination versus the side that didn’t.
