It’s a Lemmy thing. Basically latency limits the maximum number of activities that can be sent per second (they’re sent like TCP: serially, and each must be acknowledged). When LW has a LOT of activities to send out, they can get backlogged if there’s significant latency between LW and other federated servers.
That’s the gist of it, anyway.
Oh, I was just lamenting that such a garbage post is contributing to the backlog because of the activities it generates (which LW has to federate out since its “owns” the community this was posted in). Basically a potshot at a low-effort, shit take of a post.