On my browser (Firefox, on OSX) it loads /loading then /login. When I go back, that takes me back to /loading, which forwards me to /login again immediately.
Going back requires holding down the back button so I can skip that history record. Illustrated: https://imgur.com/a/zFaGw4a
(Quite a few sites screw this up. It's very annoying.)
This is great, thank you for sharing. We primarily test in Chrome which doesn't seem to display this for whatever reason. Should be an easy fix to remove the history for the loading page.