And here I entertained the thought that for Google the legislation was a form of regulatory capture.
If this is not working out for Google, perhaps it's because the business is fundamentally incompatible? But I have problems believing that. The outcome would be too good :-)
After having read most of the GDPR, that's my conclusion: all advertising other than 1990's style bannering now needs per publisher, per user, opt-in for anything that does tracking or is personalized, where the default should be set to 'no', denying should be as easy as consenting, and refusing access is not a valid publisher response.
That means i.m.o. that using any form of modern advertising has become illegal under GDPR, unless you get users to consent in a compliant way, and I have seen just a few sites even try. I think Google is scrambling to understand that their business is now mostly illegal in EU.
If Google hosted the ads, how would they not collecting your browsing habits? It's the same as with the embedded Facebook Like, which is in the same ballpark.
Counting impressions and clicks are no problem, as long as no personal data is collected. But storing personally identifiable data for the click/impression (such as the full ip address, or advertising id in a cookie) needs consent. Unless you need (and only use it) to prevent fraud, which is a valid legitimate interest. Using it for (Re)marketing is not.