I am pretty sure the "full coverage" button for the Top Stories section is new but it is not exactly what was demonstrated at Google I/O a few months ago. Glenn Gabe spotted this yesterday, posted it on Twitter and I can replicate it - where Google shows a larger Top Stories with a big Full Coverage button that takes you into Google News.
Here is a screen shot of the button:
At Google I/O they said this full coverage would show story timelines, podcasts, and so much more - plus the UI is different. You can see those screen shots over here. I did ask Google what is new here and hope to hear back today.
Here are more screen shots from Glenn:
Here's another example of the "full coverage" feature with Top Stories. I'm seeing this in Chrome and via the Google Search App. Could clearly drive a lot of traffic to Google News proper. pic.twitter.com/6dMMGduEjO
— Glenn Gabe (@glenngabe) June 13, 2019
After I click through, I do get "top coverage," "videos," and "twitter" results for this topic:
This may lead to a lot more traffic to some Google News sources and maybe to more videos and tweets. Or it may lead to less traffic if you were doing well - it just seems like Google is driving more diversity into these results - unrelated to that diversity update from the other week.
Forum discussion at Twitter.