Google started testing hotel highlight icons in May of 2018 and rolled them out around the same time. Not Google is testing expandable highlight icons which provide more information about different amenities, features, and highlights.
The first difference from the current design that users can notice in this test is that the icons are rounded and shadowed instead of the normally flat icons. They are designed to look and feel like something users could click on.
Clicking on a highlight icon brings up a highlight window with a selected highlight information. The window is a carousel where users can swipe left and right to see more information about different highlights.
Depending on the highlight Google can either let you know that a particular amenity is a rare find for hotels in the selected area, or give it a rating from 1 to 5, which seems to be the average of all user reviews mentioning the highlight.
Also, Google can show relevant photos and reviews (sourced from different sites).
I have almost no doubt Google will roll this feature to mobile devices sooner rather than later. Roll out to desktop will follow. So, it’s extremely important for hotels to check their amenities and offering in Google My Business and ensure their accuracy.
Here are more screenshots of the feature for different highlights: