Google is going to be dropping and removing the feature in AdWords to show review extensions in your ad copy. This month, the review extensions will be gone. Steve Seeley posted first about it on Twitter and Ginny Marvin posted a more detailed write up about it on Search Engine Land.
Google AdWords review extensions launched in 2013 and I believe many advertisers like the outcome. But Google posted this message in the AdWords dashboard for advertisers using the ad extension:
So if you are using them, this is a heads up that they will stop working next month and that you should download the extensions now.
Forum discussion at Twitter.