I found this problem by chance from friend.
The friend created a GitHub account a few months ago with email address and password. He did not set anything and always used the default setting. He used the github account only to report issue (bug report) because of an app.
A few months later, the friend no longer has an email account because the email provider is dead. So he wanted to see if he could log in to GitHub, no he couldn’t.
His GitHub account was automatically deleted, so it was censored. All his bug reports are gone.
I can also confirm this problem, the problem is GitHub deletes your GitHub account if you use the default setting and only email address and password.
If you create bug reports e.g. for an app and have no email account e.g. because the provider is dead or for other reasons. When someone replies to your bug reports, GitHub automatically sends notifications to your email address.
Since the notifications cannot be delivered, the GitHub system recognises this as an error and automatically deletes your GitHub account along with all your bug reports. It is also no longer possible to open your reports externally, it is simply censored automatically.
As a test, I created this report here and deleted my email account and only use the default setting. Let’s see if I get deleted automatically after a few weeks or months. The requirement is that the user gives any answers and saves this report, so let’s see if I get deleted.