Regarding the Private DM's, we had to issue a retraction. Fediverse clients only started adopting federated edits relatively recently. Prior to that, people relied on "Delete & Redraft", which attempts to send a delete that may or may not go through, and hand the user the content for editing. 

In this case, the DM was actually a Public post that accidentally had the wrong scope applied. The time and content matched up perfectly, and the delete request did not correctly remove the content from mastodon.social's cache. When Maven ingested posts, they did so from a public firehose endpoint for that server, rather than use federation as intended.