Since you seem to be a little thick: you’re being called a Nazi apologist because you’re effectively providing excuses for why Russia’s fascist dictator was right to invade Ukraine, or at the very least isn’t to blame. It’s a horseshit narrative because Putin alone is in charge of his army and Ukraine has not done anything a sovereign nation shouldn’t be allowed to do.

It’s a direct attack on your position, which appears to apologize for a fascist dictator invading a sovereign nation. It’s neatly wrapped in the form of an insult, but that doesn’t make it an ad hominem by and of itself. For that to be the case, he’d have to call you a Nazi and not bother addressing what you said. But he directly addressed it, by stating that he believes your argument is apologizing for a fascist dictator. Hence it attacks your position, hence it’s not an ad hominem.