This has nothing to do with federation, reddit was a single system and had the exact same issue. It’s simply a result of having communities that overlap in topics, or articles that are relevant for multiple communities.

The key is that each of these posts has a different discussion due to the different community it is in, isn’t that good?

I think I saw one of your earlier posts and I really appreciate you chasing this down and raising awareness. As a relatively savvy user this is definitely something I’ve noticed and I share your concern that it will slowly erode user’s trust in the concept of federation.

Technically, can you trace where the comments are dropped? does the target receive the response but fails to process it, or does it break somewhere at the network layer? if so, is there no receiver “ack” built into the protocol? sorry for asking a bunch of questions and feel free to ignore (I’m an engineer but I don’t know much about the federation protocol…)

I wonder if some instances are more prone to drop comments that others? have you looked for example at lemmy.world (very large but performant) and another relatively small instance?

Absolutely, I’ve done more posting/commenting/upvoting in the last days than I’ve done on reddit in the last year.