We seem to be having trouble with a handful of the larger lemmy instances, as well as some misc other instances even though these instances aren’t dead-dead: https://fedia.io/federation (at bottom of page - “Dead Instances”).
I thought maybe it would’ve been a problem with a specific lemmy version, but there are several versions in the list and also some still-living Mastodon instances that are running reasonably up-to-date versions.
Somehow I don’t think a comment here will get the reach needed to keep your hair in 😅 I’m surprised that some instances would have a disproportionate report rate! (other than maybe the more polarizing ones like lemmy.ml)