Non-functional, no obvious changes to the rendered webpage let alone a "reader mode" rendition. Possible malware - it's sending information from the browser to extensionpay.com, idk what (encoded, haven't bothered to look closer). This looks like trouble - steer clear of it.

What is going on, Mozilla? Have you completely stopped policing new extensions? You can't blithely warn users "Make sure you trust it before installing" without providing means or at least guidance on HOW THAT MIGHT BE DONE. Very irresponsible of you.