Firstly - there is no workable “definition” of fascism that’s remotely useful. Not yet, anyway. It probably has something to do with the fact that fascism isn’t so much an ideology but more a function within the modern liberal nation state - ie, the people who perform the violent repression for the benefit of the rich elites at the top. Sometimes, the elites become so frightened that they will literally hand the very state over to these people in it’s entirety - as happened in Germany and Italy (and other places).

Secondly - these people calling themselves “conservatives” and/or “libertarians” don’t actually care much about labels. The fact that they actually call themselves “conservatives” (essentially a dead ideology they wouldn’t recognise if it bit them on their behinds) and “libertarians” (a term that originally described anarchist and other libertarian socialists) without having the foggiest clue what those terms really mean is a clue. The only thing they understand is that it’s a term they can throw at any people pushing back against their vile (and often fascist or fascist-adjacent) narratives.

That’s pretty much it.