14 years ago, GNOME developers decided that if a system only has one user and session combination, the logout button should not appear.
Because the Wayland migration kept X11 sessions around for years, that behavior never actually surfaced in practice. Now GNOME 50 ships without an X11 session, so the logout button disappears, confusing users and even GNOME designers.
People are now discussing whether that behavior still makes sense, and simply restoring the old button is not the full answer. It is a funny reminder that deployed code can become hidden tech debt and stay dormant for years until a platform change exposes it.