The post about the IRC channel is
here. There is also a Discord server that you can get into (post about it
here). The channels are bridged, meaning messages are mirrored between them, so you shouldn't miss out on content by only being in IRC or only being in Discord (except for eg the #voice chat, which isn't relevant to IRC because IRC doesn't transmit voice).
As specified above, there are logs of the IRC sides of these channels
here, which gets a lot of the Discord chat by way of bridging.
We have so far been using #meta on Discord (bridged to #glowfic-meta on IRC) for discussion about Discord and optionally other topics like the Constellation. It might be convenient to keep all the Constellation-meta discussion together and not have it interspersed with server-meta stuff, but I don't know we have that much server meta stuff going on anymore anyway. (There was a little the other day about author channels.)