In the recent devlog it says they closed them. They now only use Irrelevant's twitter and itch to announce stuff. They did this to focus on the projects without having to worry about managing the discord and twitter accounts. Makes sense I guess.
Darn. That sucks. That was probably the only Discord Server that I was active in. Lots of good art being shared there too. A shame, really. I wish they just let it continue while also focusing on the game.