Now using Firefox, v82 x64. Firefox has re-added the RSS feed option at some point (switching over from Chrome) and Newsblur is not an option. So, I went to the Newsblur site and saw the item “Firefox: Register Newsblur as an RSS Reader” in the Goodlies & Extras". But nothing happens.
The URL showing for the link is “https://newsblur.com/#” which goes nowhere.