Afaik it was there when I joined over a year ago. Discord hides some channels by default now when you join a server, that could be it. It is always a shame when a FOSS project uses Discord more than Matrix, makes me way less likely to interact with the community.
Bluesky is such a huge improvement over twitter and so many people are just ignoring that. Yes, the app is centralized, but you can still host your own data if you choose. Plus, the customizable feeds, algorithms, and moderation lists are all great.