Does not remember your choice, so every time you come back to a page or navigate to a different page on the same site you have to increase it all over again. Maybe this is acceptable on desktop but it's borderline useless on mobile Firefox where pressing the button requires four taps and scrolling through the list of extensions to get to it.

Edit: I'm not "using the review page as a support forum", I'm reviewing the extension by pointing out a feature it does not have but which people probably expect it to.