The image on the right shows how Google News would typically show "trending topics" on the left hand news filter bar. But that no longer shows up on the left bar, instead you just see the general categories of news such as World, U.S., Business, Technology, Entertainment, Sports, Science, Health and more.
The issue first appeared yesterday and was reported on February 12th and posted in the Google News Help and Google finally confirmed it the other day.
Stacie Chan from Google said in the thread:
The TCs are right. They indeed notified the team and a fix is being worked on. Trending Topics should reappear shortly!
I am not sure exactly when this feature will return, but it is definitely still missing at the time I am writing this.
Google Trends at google.com/trends still works fine as an alternative.
Forum discussion at Google News Help.
