Many still don’t understand that ALL your activity on public relays is public, this includes all your encrypted DMs. The encrypted data is all public, ppl just can’t read it without your keys.
Discussion
In Iris the message channel id was hash(shared secret + recipient public key). This would hide who you're chatting with, but you had to subscribe to channel ids from everyone you follow and you couldn't receive messages from strangers without an invite link arrangement
When you log in with someone's npub, clients should show their chat list as a reminder of this fact
Indeed
Is it a feature or a bug ?
The problem is not realy that encrypted data can be seen as encrypted but that metadata (source and destinatiion pubkey) is available. With these information, you can construct a social graph.
Yes, the metadata is still public info too. Also if you can copy the note from your DM messages and paste it in as a public post it’ll show the meta data but the content will be encrypted. Also, relays can see who has contacted whom and maybe also metadata of users in encrypted channels