Google has a new requirement for product review feeds: You need to add the review_id attribute. The review ID is a unique identifier that can be used only once, similar to a product feed, with the ID attribute unique to the product itself.
Effective from 8th July 2024, Google mandates the inclusion of the review id in your product review feeds. Failure to comply with this requirement will result in your reviews being disregarded, potentially affecting your performance on shopping ads and free shopping listings.
You can see your missing or invalid product_id here: https://merchants.google.com/mc/productreviews/diagnostics.
The review is missing the Review ID. A Review ID is a permanent, unique identifier for a product review and is required to uniquely identify each review. The ID won’t be shown to customers, however, you can use the ID to look up your reviews. Update your review feed to include the attribute with a unique value for all of your reviews. Refer to our feed guide to understand how should be implemented in the feed.