As an (USA) outsider, let's see if I get this right...
Trump said that "communists, Marxists, fascists, and the radical-left thugs" live like vermin in USA. Then Biden compared him to Hitler.
And only Trump's language is the problem, not Biden's?
So as a non-American, what you're not seeing is that none of these words are ever applied correctly in the US. The "communists, marxists, fascists, and radical left" that Trump is talking about are all words he uses to describe anyone who disagrees with him.
For instance, those fighting for transgender rights are commonly labeled Marxist fascists by Trump and his supporters
Yes, he calls people who he disagrees with "vermin" (which is bad) and Biden calls him Hitler and his supporters MAGA terrorists (which is bad). So, one is OK by Lemmy, one not. Interesting.