Revise your pricing strategy
In the first-price auction environment, price floor optimization doesn't allow buy-side algorithms to lower your CPMs over time, not in a single auction.
If you analyzed historic closing prices and set a $4.9 floor for both auctions in the example above, Buyer 1 would have lost the second auction with $4.5 bid. As a result, the buy-side algorithm would bid higher in the next auction to improve its Win Rate.