I've never run a Lemmy or kbin instance, but have run a mastodon instance and am familiar with distributed systems in general.

Probably both the source instance and the destination instance have a queue of federated messages to process and the message needs to be sent to the destination and processed into the destination database respectively before it'll show up on the destination of the worker threads get overwhelmed.

I'd imagine that recently with the influx of users, activity, and the size of the federation, a number of instances probably sometimes have some pretty deep queues to work through at times.

Ten hours isn't ideal and hopefully isn't common, but doesn't seem out of the question in the case of connectivity issues or spikes im activity.

I've noticed this too.

Posting from Kbin has got a delay to it.

I've noticed about a 10 minute catch-up time between beehaw and kbin.

I just had a 3 hr delay posting to a community on another instance and 4 posts haven't gone through after 12 hrs to a different community on same instance. One comment missing also.

Looks fine on my end, nothing if I browse the instance directly.

Some had been in limbo for several hours, so I deleted and reposted one, and it showed up immediately. So I think sometimes things fail to send over, which is unfortunate. Hopefully some better checks get added in for that.