this isn't a unique problem for the Fediverse. sometime in ~2018, Mastodon (IIRC -- it might have been a specific instance) implemented inter-user messaging ov

this isn't a unique problem for the Fediverse. sometime in ~2018, Mastodon (IIRC -- it might have been a specific instance) implemented inter-user messaging over ActivityPub, showing users only messages addressed to them -- since it wasn't actually part of the spec, the rest of the Fediverse saw them as regular feed messages. Mastodon users assumed DMs were private and got burned, other instance operators were all of a sudden flooded with non-post messages, and everything was generally pretty suck-y until everyone got their shit together. this sort of thing happens periodically (see: Gab's federation flooding the network in a similar way), it's a consequence of different entities trying to develop individual features over a unifying protocol.