Google just announced this week a new algorithmic update to not show review markup, review rich results, in the Google search results for specific cases. You can learn more about those new rules over here. And it looks like Google is acting on it. According to Moz and RankRanger's tools there is a 4 to 5 point drop in the rate these review rich results show up in Google search.
Moz is showing a dip from 39.2% of the search results showing review rich results to 35.8%:
RankRanger is showing a dip from 42.5% of the search results showing review rich results to 37.3%:
So I guess this update has bite to it.
Hat tip tp Brodie Clark for noticing this first.
Forum discussion at Twitter.
Update: Also SEMRush shows a drop:
A reviews drop also shown in @semrush sensor in mobile and desktop top 20 results across most countries too : https://t.co/Lihi95TEwW cc @rustybrick @brodieseo pic.twitter.com/l5GLE4HNAA
— Aleyda Solis (@aleyda) September 18, 2019
