On Firefox 85.0.2 (64-bit) using my MacMini 2018, I get the message "Service Temporarily Unavailable" on any Amazon UK listing... I have tried several listings and get the same message. This add-on is nothing more than useless. However, the website is an amazing tool in itself - it's a shame the add on is not what is described.

the issue is that that icon in the toolbar is now missing and there's no way to get it on there. so, despite being labelled as working with firefox 57+, it actually doesn't. hopefully it gets fixed soon, it's pretty great otherwise