Yep i can. Ive helped out on both lemmy, piefed, mastodon, gotosocial, peertube and others. Little things mind but yeah its my day job.

Theres a queue that is part of different instances. What can happen is posts/comments get backed up and the queue takes them all in. When an outage or slowdown happens it can bog down certain servers. Threadiverse (piefes/lemmy/mbin/etc...) up/down votes, comments, posts, etc... it gets slower as more instances connect to others. Its unfortunate but its part of the fediverse protocol. Piefed has some advances there, but it can still get bogged down sometimes.

Im not saying thats definitively what it is, but ive been on the other side of this phenomenon a couple of times when my lemmy and then later piefed instance had a new instance sync with it. Lemmy.world has had this issue for a while since its one of the biggest.

The way to test is to sent the instance in quesion a POST request with a comment OR use a known good instance (like piefed) and check the logs. It usually comes back with either a 200 immediately (which is good) or theres a HUGE delay.

Most of these instances are very much volunteer efforts.