I'm not actually seeing too much of this. Most leftists are relieved by the win, I suspect, and beyond that just really tired of having to fight for things that ought to be our by right -- ownership of our bodies, for instance, and the right to vote, and the right to say what we think is true, even if we are working as teachers in public schools.
Anyway, here's Scalzi's take:
Likewise “your vote shouldn’t count if we don’t like it,” is also something of a non-starter for a lot of people! Having the GOP become the political face of US authoritarianism in a moment when authoritarianism, including sham elections for political advantage, is being actively (and popularly!) combatted in Europe is not a great look. I also think the political strategy of trying to separate out trans people for persecution, popular as it was and is with the intolerant, was not particularly smart. Trans folks really are a small sliver of the population, but everyone understood the point for the GOP was and is to start with trans folks, and then just keep going to gays and lesbians and then to other groups, including, inevitably, the Jews.
On Twitter, people are furiously pointing out to each other that yes, it still does matter if we take Georgia as well. Couldn't agree more with that one.