On Special:WhatLinksHere the "previous X" pagination link is broken, it only allows you to get back once.
The "previous" link on this page leads to https://en.wikipedia.org/w/index.php?title=Special:WhatLinksHere/Main_Page&from=15586&back=15586
Apparently it simply uses the "back" parameter as the new from, but isn't able to backtrack any further; you can thus only get back one page, not more.
I've tried this on an old 1.15 so I'm assuming this never worked as intended.
Reported by [[:en:User:Peter James]], https://en.wikipedia.org/?diff=612777264