This has gone on pretty much as far as I know, surprised no one else has asked it.
When a new user joins a room (under 20 rep - I believe this stopped happening with accounts created after the lobbies), they don't have a name or avatar.
So, when you click on their profile, it says that they don't have the same username here, then provides a link to why.
When you click the link, it takes you to https://chat.stackexchange.com/faq#avatar, and #avatar does not exist, so it doesn't show you why their avatar is not showing.
