I've heard that many leftists are avid supporters of grooming, especially forcing their kids to attend drag shows, or trying to make them (boys) wear dresses to be "inclusive" (happened in UK schools).
On top of that there's the whole push to convince boys that they're girls and try to turn them into girls by mutilating them either surgically or chemically.
To them 'Nazis' is anyone slightly to the right of them and anyone who would dare call them out for pushing their agendas, on children no less. They know deep down that they're in the wrong, not us, which is why they're so reactive and loud about it.
They probably also think that we're just magically going to stop existing if they de-federate from us and anyone connected to us, we'll still be here though, they're not getting rid of us, they're just doing the Fediverse equivalent of covering their ears and shouting LAH LAH LAH so they can't hear us.