We would like to inform you about a few changes that impact your ability to create Custom search style experiments, specifically for your Related search styles in your AdSense account.
Beginning May 10, 2021, you will not be able to create new experiments for your Related search styles in your AdSense account. Your existing Related search experiments that are currently in progress will also stop on May 10, 2021. Please note that this change does not prevent you from creating experiments for other elements of your styles (e.g., search ads, shopping ads).
Our engineering teams are working hard to bring this functionality back by early July 2021.
Thank you for your understanding and we apologize for any inconvenience caused.