I am not sure if this is new, to be honest, we saw something super similar in the normal local review summaries about fives years ago with "X people mention [keyword]." Now in the Local Service Ads, they have it where it has this people icon with "Reviews often mention [keyword]."
This was spotted by Anthony Higman who shared the following screenshot on LinkedIn:
Here is what it looked like five years ago in the review summaries:
Of course this makes you wonder how important words in your reviews are for ranking here.
Forum discussion at LinkedIn.