Update: This feature has been seen by some users since July, but was added to mobile results fairly recently.
Google added review refinement bubbles to Local Knowledge Panels. The bubbles are available on mobile and desktop devices. The bubbles show the most mentioned terms within reviews and allow users to read more reviews about a certain highlight they might be interested in. Here is an example of what this feature looks like for a Toronto bathroom renovation company Happy Bathroom Renovation:
Here are some of the top things users talk about when reviewing CN Tower and the White House:
Similar bubbles have been available on many local review sites (e.g. Yelp, TripAdvisor, etc.) and even within Google’s own product knowledge panel reviews and, I believe, in hotels’ local panels for a long time, but I believe they only recently were added to GMB panels across all verticals.
I personally welcome the new addition, as I tend to use quite a bit on other sites to see what people mostly happy or disappointed with.