A 'bug' in DM messages

First of all i am not sure is this reported before or not, whatever.. who cares?
I had a friend in Discord, a few days ago, i had to unfriend him, and i did.. after this, he's pinned a message on Discord, there was no mutual servers and he was not added in my friend list even. he's pinned a message, and i have noticed this because there was a notification from the dm, the peoples who wasnt my friend can pin message(ofc if theres a message in the past) and he can edit his messages even.. in my view, editing and pinning his messages can be a trouble for discord community users, and its a trouble for me this should be fixed and as the last, im not sure if he's doing it on pc or mobile.