Please try to comment and post things now, and see if they federate again.
Hopefully you see your activity instantly federated. I have tried making comments both to instances running Lemmy 0.19.1 and 0.18.5 and they all federate like they should.
Hope you have the same experience! 🥳
Yes, it seems federation still is buggy. :/
Your comments are on lemmy.world now but they needed a Lemmy software restart to make them federate:
https://lemmy.today/post/4778593 => https://lemmy.world/post/10236722
https://lemmy.today/post/4786719 => https://lemmy.world/post/10236757
So still gremlins in the software…