That’s a Mastodon thread. This is Lemmy.
While Mastodon users can subscribe to Lemmy communities (such as this one: !linux@lemmy.ml or lemmy.ml/c/linux ) and see Lemmy posts in their feed, Lemmy users cannot normally comment on Mastodon threads.
Mastodon users can post to Lemmy communities by mentioning the Community ( !KDE@lemmy.kde.social in this case). That allows Lemmy users to comment on it.
Nice! I missed that.
So Lemmy communities have a third form:
- The URL format for non-Lemmings: https://instan.ce/c/community
- The Lemmy format for Lemmy clients: !community@instan.ce
- The Mastodon “tag” format: @community@instan.ce