I have a feed – https://govtrackinsider.com/feed – that hijacks the whole browser window and redirects me away from newsblur to the homepage of the website. This occurs only in the desktop browser version and happens even in feedview.
I have sometimes similar problem with http://gdansk.naszemiasto.pl/rss/artykuly/476.html feed as unread article gets whole browser window on folder/site activation.
It looks like it is somehow related to story mode as it executes query similar to
https://newsblur.com/rss_feeds/original_story?story_hash=6518549:3b1897 and opens it using whole page,
other feeds use https://newsblur.com/rss_feeds/original_text?story_hash=6518549:f6c9cc and it looks ok.