In 2020, we launched first-party cookies from Google to help you increase your revenue with features like frequency capping. Now, we've updated first-party cookies to also support personalization.
First-party cookies for personalization help to show personalized ads to your users when third-party cookies aren’t available, which may increase your revenue. Note that you can only use these cookies for personalization if you’ve turned on the "Allow first-party cookies" option.
We've added a new control to the "Ad serving" tab in your account to let you choose whether you want to allow first-party cookies for personalization. To access the control, click Brand safety 
Learn more about the "Use first-party cookies for personalization" control.