A number of Armenian news outlets’ RSS feeds  are giving HTTP Error 403 in Newsblur for a month now, though working fine in Feedly and Inoreader. The problem is due to security precautions taken by media in recent weeks.
I’ve counted 5 websites so far, and was able to contact one of them to whitelist Newsblur, but there might be more. Though it’s possible to contact each website separately to whitelist Newsblur, i think the issue is with Cloudflare (as only Newsblur seems to be affected. UPD. Inoreader is also affected).
As a side note: I’ve come across a related discussion on HackerNews where CTO of Cloudflare suggested contacting him to sort out the problem.
 https://hetq.am/en/rss https://mediamax.am/en/index.rss https://stickers.panarmenian.net/feeds/eng/news/