Google had updated the Shopping ads Policy Center and free listings Policy Center to "better explain" the policies and how Google enforces those policies, the company posted.
Google also posted a clarification of the YouTube Shopping ads requirements and Discovery product ads format requirements to ensure retailers can better understand why their ads may not be serving and how best to resolve the issues.
Google also said they updated the Google Shopping Help pages for Recommendations & personalization and How Google Shopping Works to better explain how Google's ranking works.
If you want to dig into what changed, I recommend you through those URLs into the Twitter.