As a reminder, back in 2016, Google updated its guidelines for using schema markup on your site with third-party reviews. Google reminded us in 2018 that this is not in accordance with their rich results guidelines. And now, John Mueller of Google reminded us again - he said "You can't mark up 3rd party reviews with structured data."
In short, the markup should only be added to first-party reviews that are first posted on your site. If others take the reviews from your site, they should not markup those reviews. If you take reviews from third-parties, even through a licensing deal, you still should not use markup on those third-party reviews.
John added on Twitter "but feel free to show them on your site without the markup."
Here is his reminder:
You can't mark up 3rd party reviews with structured data, but feel free to show them on your site without the markup.
โ ๐ johnmu.csv (personal) weighs more than 15MB ๐ (@JohnMu) June 29, 2022
For not indexing a part of a page, there's no simple solution. Sometimes data-nosnippet is enough though.
One other note, related to the use of review snippets on Local business listings. This is also not new, but Google updated the top of the review snippet docs by where it says "Local business" to expand that at the top to read "Local business (only for sites that capture reviews about other local businesses; see the guidelines about self-serving reviews)." This links directly to an old guideline that reads:
If the entity that's being reviewed controls the reviews about itself, their pages that use LocalBusiness or any other type of Organization structured data are ineligible for star review feature. For example, a review about entity A is placed on the website of entity A, either directly in their structured data or through an embedded third-party widget.
Hat tip here to:
Google made an update on the review snippet guidelines (clearer now)- The guidelines emphasize that Review snippets can generate rich results for the local business type only for sites capturing reviews about other local businesses. See the added sentence๐:
— Naomi Gallula (@naomig84) July 6, 2022
FYI- @rustybrick pic.twitter.com/cOOgQJGtWt
Forum discussion at Twitter.