After sending a DM, the profile lacks access to it. I can see my posts and public comments, but not my DMs. Thus there is also no way to read or edit DMs Lemmy users have sent.
update
As @viking@infosec.pub points out, sent messages are accessible in the ALL tab. Once my DMs are rendered, indeed there is an option to edit them just like a public message. But presumably due to another bug, Lemmy recipients are not likely notified of edits (untested).
If I go to the inbox and switch the view to “all messages” it shows my sent and received messages.
But yes since all messages are federated, even personal ones, you can’t edit them.
Ah, right I overlooked the ALL. I was sure I had been able to reach sent msgs in the past but forgot how and wondered if the option had been removed. I just corrected the title and added an update.