You don't seem like some other people on this platforming who complain about the left in strong words, so let me tell you what I think

There are and always will be fringe morons, who support literal communism or nazism, so a few posts you found on Twitter isn't proof of those ideologies rising. What most leftists in America, and actually by now the vast majority of the country, want is for example to expand the already existing program Medicare to not just the elderly but everyone else. They also want to do what has already been done for primary school and high school, and do that for college as well, making it free-of-charge for those who attend it. Both are supported by about 75% and 60% of the American people respectively.

Then there's some really non-controversial stuff that almost everybody regardless of ideology can get behind, like ending the offensive wars, decreasing military spending (maybe 1.5 as much as #2 China would be enough, we don't need the current 3x), legalizing marihuana, and getting the influence of corporations out of the political system, in other words making sure bribes aren't legal as they currently are.

Barely anyone outside from some crazy college kids is actually for actual communism. All that these new wave of progressive Democrats, not taking corporate PAC money, as well as the entire country, actually want is not communism under a new name, but to expand a few programs that already exist. That's barely "super radical", unless Medicare For All Seniors and free primary and high school is also "basically communism"