Google today announced that is retiring the ad balance feature from all AdSense accounts on May 20, 2020. The ad balance experiment option, including all completed ad balance experiments, will also be removed.
According to Google, publishers currently using ad balance or running ad balance experiments will receive an email with additional information.
Google says that going forward will focus on developing the suite of blocking controls instead.
Ad Balance was rolled out in Google AdSense, back in 2018. Ad Balance was a feature that enables publishers to reduce the number of ads shown (the ad fill rate).