Facebook is testing a 'breaking news' tag for developing stories
 

Facebook will set a cookie to keep you logged in, but it won't set one to remember whether you want to stick with a chronological News Feed. That sort of thing makes it hard to tell at a glance how old a story from a media outlet in your Feed might b...

https://www.engadget.com/2017/11/29/...ing-news-test/