I noticed this change in a 234x60 format Google ad on my blog (see the screenshot) The feedback link appears rarely so probably Google is still testing the change.
What are Ads by Google? Site visitors can click the Ads by Google to send feedback to Google about the appropriateness of that specific advertisement or general feedback about the website displaying the Google ads or report a Google policy violation.
Earlier, only Google Adsense Premium Publishers were able to display the "Ads By Google" text and non-premium Adsense publishers were served the "Ads by Gooooogle" link. If the website is displaying Alternate Ads, Google will not display 'Ads by Google.' link.
If you see a Google image ad that you feel is inappropriate or misleading, click the Feedback: Ads by Google link below the image ad. Using this link will flag the ad for additional review. You can even send suggestions to help us improve Google AdSense program using the link.