I noticed this when I wrote the AGC extension a few years ago. Very annoying!
It is not really possible for AGC to fix but there are common cases it fixes.
// We also need to fix up any "/" characters that have been removed
const possibleLinkPrefixes = [
["http:/search.findmypast.co.ukrecord?", "http://search.findmypast.co.uk/record?", "Findmypast"],
["https:/search.findmypast.co.ukrecord?", "https://search.findmypast.co.uk/record?", "Findmypast"],
["http:/www.findmypast.co.uk/", "http://www.findmypast.co.uk/", "Findmypast"],
["https:/www.findmypast.co.uk/", "http://www.findmypast.co.uk/", "Findmypast"],
["http:/search.findmypast.co.uk/bnaviewarticle?", "http://search.findmypast.co.uk/bna/viewarticle?", "Findmypast British Newspaper Archive"],
["https:/search.findmypast.co.uk/bnaviewarticle?", "https://search.findmypast.co.uk/bna/viewarticle?", "Findmypast British Newspaper Archive"],
["http:/search.findmypast.co.uk/", "http://search.findmypast.co.uk/", "Findmypast"],
["https:/search.findmypast.co.uk/", "http://search.findmypast.co.uk/", "Findmypast"],
["https:/books.google.combooks?", "https://books.google.com/books?", "Google books"],
];