Google announced on September 16th, 2019 that they would be making major changes to how they display review rich results.
The biggest changes, that are still rolling out, affect rich snippet star ratings for the
Organization Schema types.
These will no longer show ratings stars if the Structured Data markup for the entity (business) is embedded on on the business website itself, either manually or via a third-party widget.
With this change, we’re limiting the pool of schema types that can potentially trigger review rich results in search. Specifically, we’ll only display reviews with those types (and their respective subtypes):
This change seems specifically aimed at sites manipulating review Schema to show stars in organic search results.
Google representative John Mueller also confirmed that this will also affect third-party widgets that embed review markup, that have up to now, provided ratings stars in organic search results.
I double-checked to make sure 🙂 — that's incorrect. Regardless of how the reviews are embedded on your site (widget or not), if it's for your own LocalBusiness/Organization, they would be considered self-serving and not be shown.
— 🍌 John 🍌 (@JohnMu) September 17, 2019
As of September 23rd, 2019 this is still rolling out. I still see review rating stars for numerous sites that are using either manual Schema markup or embedded third-party review aggregation widgets.
Google said that third-party sites that independently collect reviews would be unaffected by this change. This would seem to indicate sites like Yelp, Facebook, YP.com, HomeAdvisor, UpCity, Clutch.co, Angi, BBB, and others would all still display their star ratings (where they currently appear) in search results.
Only review markup embedded on the site of the business being reviewed would be considered “self-serving”. This means both manually implemnted Schema markup and third-party widgets designed to output
aggregateRating Schema markup.
Also, leaving the Schema review markup in place will not earn you a manual penalty from Google, the stars will simply not be shown in organic search results (the “ten blue links”), once the changes finish rolling out.
More information is available at the Google Webmaster blog: https://webmasters.googleblog.com/2019/09/making-review-rich-results-more-helpful.html