Update on this issue. Reddit has apparently started to enforce login requirements for RSS feeds. Since most newsreaders have elected to not pay Reddit for API access, most of them will likely stop working.
However, there is a workaround for now - you can use old.reddit as the feed url, so something like old.reddit.com/r/technews.rss will work, for now.
I expect Reddit to also kill old.reddit at some point as they still have a couple of bullets in their gun to shoot off the rest of their foot.