It's a split meme that refers to the emotional rollercoaster of a prolonged uncertain situation whenever news come in.

Its two parts are "It's so over" when there's bad news and "We're so back" when there's good news.

Back to annoy us with inane Twitterisms, I reckon.

It is kinda funny once you get used to it. When there is bad news they say “it’s so over” and good news “we’re so back”. The emotional rollercoaster on LK-99 is pretty intense and these phrases capture that for people. I get it at this point.

So it's the same as the Bob Ross memes of "Ruined", then :)

It's a relief valve for crowd mania. Humans really love to communicate in jokes, especially when those are in-jokes.

X-isms

Life on twitter teeters on the edge separating intense excitement and horrific despair, and “we are back” means we’ve switched from one side to the other again

I wished they would keep it on Twitter and elsewhere and not bring that crap to HN.

While I agree with your sentiment, the phrase "we're back" is at least as old as the film (1988) Coming to America, probably older.