My browser / operating system: Windows NT 10.0, Chrome 85.0.4183.83, No Flash version detected

While I was going through the forums, I noticed something extremely awkward, a user that had 0 posts:

Yet, there is an existent post of theirs in a topic.
I will not say what the user's name or what post it is, but what are the possibilities in getting this error?

If someone gets a 404 error from their first post, then that will happen.