The Daring Fireball JSON feed https://daringfireball.net/feeds/json stopped being parsed on 2025-07-16 18:12:55 with the error message Not an RSS feed (553). It was parsed beforehand with no issues. Does NewsBlur no longer support JSON feeds?
I dunno about the JSON aspect, my Daring Fireball feed is https://daringfireball.net/feeds/main and works, got stories now