The internetbro logical fallacy revolution and its consequences has been a disaster for human discourse.
This is not a formal debate so drop the pretense already.
Also note that labelling a Nazi sympathiser as "a defender of fascism" is not an ad hominem, that's a description. Just because you personally object to the label doesn't mean that therefore it's a logical fallacy.
Also note that there's no generally logical proposition in the statement of opinions. "I don't like mint icecream" could very well be considered an ad hominem against mint icecream by these clowns because anything they disagree with which is a statement of opinion counts as a logical fallacy in their eyes.
But if there's a layperson's discussion going on then the notion that the "debate" is focused on a particular topic and all responses must find themselves within the limits of that topic is, frankly, nonsense.
Yes, introducing your dislike for mint icecream to a discussion about politics is irrelevant but there's absolutely no need to use fancy logic terms like "red herring fallacy" when you can just say "that's not relevant" instead.
Likewise, throwing out a term like "ad hominem" is just a description and it's as useful as saying "that's an insult". Except it's way more pretentious and it provides the person who deploys that term with an inflated sense of purpose and logical correctness that saying "You insulted me" or "I disagree with your opinion" does not.
Imagine if these people decided to lose the pretense and got called a nerd then just responded with "that's an insult". Like, yeah, bro - congrats on figuring that out all by yourself, I guess?
The sooner that people lose "ad hominem" from their vocabulary, the better imo.
(Although on the other hand it's a wonderful red flag for indicating that you're dealing with a pompous, self-aggrandising dickbag who wants to exert complete control over the discussion, so maybe that term actually does have a good use for general discussions after all...)