So there seems to a bug in version 0.19 where outgoing federation fails and so new content is not federated out to other instances. Incoming federation works fine and the bug itself is not affecting all instances on 0.19 but it seems lemmy.one is affected. There is a fix already published with 0.19.1

@jonah@lemmy.one could you please look into it.

Link to post telling about the bug and the 0.19.1 update to fix it - https://lemmy.ml/post/9559890