GitHub reportedly fired a Jewish employee who called Capitol rioters “Nazis”

Yes, when you're Jewish and there's an armed mob of white supremacists on the street, the last thing we want to do is insult them by improper classification.

It’s not being used flippantly. There’s literal nazis running amok. With literal swastikas, SS symbols, derivative names. For years. Deeply embedded and actively organizing the mobs like we saw last week. Ran around chanting “Jews will not replace us” and murdered a woman with a Dodge Charger. Where have you been?

Don't minimize the current threat by thinking it isn't as dangerous.

Nazis committed genocide, but that's not what Nazism was. The Nazis existed and were active for years before they had the opportunity to carry out genocide, and even then many details were kept secret from the vast majority of Nazis because the leaders recognized they would lose popular support. To say the civilians rioting in the street, ransacking and assaulting as the authorities did nothing, during Kristallnacht weren't Nazis just because there were no death camps at that time is beyond absurd.

Nazism is a political ideology which combines the ultranationalism and authoritarianism of fascism with fervent antisemitism, anti-communism, and racism. To the extent that any ideology can be summed up in three words, race-based fascism is a pretty good definition. If you see someone espousing both fascism and racism, labelling them a Nazi or neo-nazi is generally appropriate. To act like nazism is some impossible level of evil that no living person could ever reach is to deny both the reality that millions of people did in fact adhere to these views in the past, and that even today a small but vocal minority see this ideology as legitimate.

Re the comparison - Yes it seems far different if you look 30's nazism as a historical artifact, in retrospect. But the genocidey things only happened pretty late in the game and was even then kept in secret for long. A better point of comparison is what happened earier, there's plenty of differences and similarities to be found there worth arguing.