Yes private repos that are deleted leave notifications behind.
GitHub has been experiencing mass waves of crypto scam bots opening repos and mass tagging tens of thousands of users on new issues. Using the issue content body to generate massive scam marketing like content bodies.
I got hit with one of these, then commented on GitHub meetsn issue about it, and ironically got a hundred notifications for everybody's comments, many complaining about phantom notifications.
GitHub has been experiencing mass waves of crypto scam bots opening repos and mass tagging tens of thousands of users on new issues. Using the issue content body to generate massive scam marketing like content bodies.