You're actually posting in a community on a different instance than yours right now.
To answer your question one surefire way to find a community on another instance is to paste it into the search bar. There are other ways you can discover a community dynamically. E.g. !lemmyarchivists@lemmy.dbzer0.com. If you're not logged in to the instance with the community you may see instructions on the sidebar for this.
I'm surprised how quickly they started doing this. Couldn't weather the protest for even two days.
You're actually posting in a community on a different instance than yours right now.
To answer your question one surefire way to find a community on another instance is to paste it into the search bar. There are other ways you can discover a community dynamically. E.g. !lemmyarchivists@lemmy.dbzer0.com. If you're not logged in to the instance with the community you may see instructions on the sidebar for this.