Meanwhile, Trump: "Crazy do-nothing democrats", "horrendous people", "the Dems are vicious"... and about 10,000 other insults whilst seizing on one offhand comment from Biden.

Biden said, "the only garbage I see floating out there is his supporters", in response to one of Trump's supporters saying Puerto Rico is garbage. Then Biden tried to walk it back by saying he meant that supporter, or his rhetoric, or whatever (and even if we deny him that walk-back, "supporters" is not all conservatives, all Republicans, or even everybody who votes Trump). Democrats mostly called this a gaffe.

While unacceptable by presidential standards, it's extremely tame compared to the things Trump regularly says about groups of people (we could even just limit that to the things he says about liberals or Democrats), and the vocal support he receives from his supporters for these statements. The fact that this got so much attention is evidence that "double standard" would be an understatement.