This is a recurring question we get,
And 99% of the time it's not a DM but an invitation note!
3 things to know about this :
There's a LinkedIn rule that when a note is sent, it's only displayed when the invitation is accepted. So, you may have stopped a campaign or an identity, but if a lead accepts the invitation 2 months later, it will only be displayed as received on that day.
When a campaign is stopped or an identity modified, invitations previously sent by this identity/campaign are not deleted.
If a lead accepts an invitation by scrolling through their LinkedIn on the weekend (which is a frequent occurrence), the note will be displayed as a message sent at that time.
One solution is to clean up invitations directly from the LinkedIn account from which they were sent: