Mike Blumenthal posted about two changes to review summaries within the Google local listings. Review summaries are "three abbreviated sentences that attempt to capture a snapshot of your business," Mike said. What is new is that Google is now testing grouping these summaries by place topics and also can show third-party reviews in these summaries.
Review Summaries By Place Topics
Place topics are an experimental feature launched in 2019 that help potential customers "find the main themes of your business through Place Topics. These main themes are based on the reviews of your business," Google wrote.
So now, it seems, Google is using these place topics to group these review summaries. Here is a screen shot from Mike:
Third-Party Reviews for Summary Cards
Mike also noticed that Google is including 3rd party review summary cards for 3rd party sites above the Google Review Summaries. You would need to scroll a lot to see them but here is a screen shot:
Forum discussion at Twitter.