Edit: All synced back up
Hey all, bit of a meta update. Currently there are ongoing issues with federation between lemmy.world and ani.social (as well as a bunch of other instances that are falling behind .world). Currently, ani.social is about 9 hours behind world in federation activities. However, the reverse isn't true. Activities on ani.social are federating out to world promptly like normal. So, it is entirely possible that community members on lemmy.world might see things like duplicate posts that no other members of the community might see.
Going forward, this issue should resolve itself. The root cause actually comes down to a couple different bugs combining for a worst-case scenario. The flood of activity that world is federating out is being caused by a bug in kbin in which some users' actions are being repeatedly performed over and over again, much faster than instances can process those actions. Combining this flood of activity with a bug in lemmy in which federation activities are sensitive to small increases in latency between servers yields an issue in which instances that are not geographically close to lemmy.world (in Finland), are unable to keep up.
I am not a dev by trade, but have been lurking in the matrix channels where these issues have been discussed. The good news is that lemmy.world has temporarily blocked traffic from kbin.social in order to stem the tide. However, this essentially prevents kbin users from interacting with the largest lemmy instance which is not ideal.
In any case, just wanted to update people on why some weird things have been happening the past day or so.