Back in April 2021, Google shared an update on product reviews designed to promote high quality content. They are now rolling out a new update, the first major update since April, that may change how your product reviews rank in search results. In particular, if you have made positive changes to your content, you may see that improvement reflected as part of this latest release. However, it's important to note that their automated assessment of product review content is only one of many factors used in ranking content, so changes can happen at any time for various reasons.
Over time they have received more feedback from users on what type of review content is deemed trustworthy and useful. Users have told them that they trust reviews with evidence of products actually being tested, and prefer to have more options to purchase the product. Therefore Google is introducing two new best practices for product reviews, to take effect in a future update.
Google has updated its guidelines for writing high-quality product reviews. The new guidelines encourage reviewers to provide evidence to support their expertise and reinforce the authenticity of their review. Links to multiple sellers are also encouraged, to give readers the option to purchase from their preferred merchant. Additional advice on creating great content can be found on Google's Search Central help pages and public forums.