I think you should stop updating this extension to only support the newest Firefox version at all times. Its just a redirector, there is no reason it needs to only support the newest version of firefox at all times while dropping support for older ones.

Some Reddit pages don't work with the redirect https://www.reddit.com/prefs/feeds/, and the addon doesn't allow exceptions. I'm using UI changer for Reddit since it works: https://addons.mozilla.org/en-US/firefox/addon/ui-changer-for-reddit/.