That's because the structure of the docs changed. You need to hit "up", which will take you to https://www.postgresql.org/docs/current/client-authentication.html, which now has the list of links. Note how the different methods used to be 20.3.x, and are now directly listed as 20.y.
I'm unsure if that was intentional in the upstream docs, but that's what makes the website behave like it does.