DM means in Instagram user ,it means the person has deleted or deactivated his or her account from Instagram. Their name will disappear and you cant message them but you can see the previous messages
When you see “Instagram user” in a DM (Direct Message), it usually means that the person either doesn’t have a profile picture or their account is private, and Instagram isn’t showing their username. It could also be because they deleted or deactivated their account after sending the message.
