I am not from the USA (or any other part of the American continent for that matter). In a thread about protests against fascism in the US, taking place in the US, I think it's fair to assume the "you" refers to US citizens. If there was a thread about Brazilian politics I would assume a similar post refers to Brazilians and that's fine IMO. US exceptionalism is real and no doubt many US Lemmy users also fall into that trap, but this particular post just doesn't seem problematic to me.

Well, a considerable proportion of these users are likely trolls/propagandists trying to fracture the non-fascists even more. It's worth remembering that many people who protested against the Democratic Party's approach to Israel voted for them anyway because they thought it was still the better alternative. There are true assholes in the world too of course, including pro-palestine ones, there are in any movement, but there is a risk that they are exaggerated and made to seem more common through the work of propagandists.