[caf]

This is ends up being effectively a tariff, though - if fewer advertising platforms can take European customers, then that allows those platforms to raise their prices for those customers, essentially meaning that European businesses end up paying more for advertising than their competitors from elsewhere.

[JAlexoid]

Nothing will happen. You know that Google does second price auctions on AdWords, right? Google literally doesn't control the price of ads

Even if you pay Google €0.01 per click, you still can get an impression under certain conditions.

[caf]

It's not about controlling the price, the effect works at least as well in auction conditions.

If the European ad-buyers are funnelled into a subset of ad auctions, the average prices in those auctions should be higher.