The source – blog.google
Google is moving AdSense to a first-price auction model. It assumes that the advertiser with the highest bid wins the battle for ad impressions, and this is what he has to pay.
Adsense now uses a second-price auction model. Its essence is that the winner is the advertiser who offered the highest bid for the ad, but to pay the second highest, that is, the price of the nearest competitor, plus a premium, as defined in advance.
Google Ad Manager and AdMob have already moved to the first price auction. Now moving AdSense to it, too, will create a unified purchasing process on all Google platforms.