> Why would it matter that the bidders are able to match up the IDs with each other, aren't they all receiving the same profile anyway?
I would guess that yes, they're all receiving – _from Google_ – the "same profile" but they also are collecting additional info that they can then share with each other and, because they can match profiles exactly, they can access each other's info about specific people.
> Wouldn't privacy advocates consider the sending of the profiles at all an issue?
I'd imagine that the profile Google has and shares is by itself fairly anodyne, but I could be (very) wrong about that. The problem seems to be more (if not entirely) that different advertisers can share info using a common profile ID.
I'd imagine that even a single advertiser would be able to perform a similar 'attack' by, e.g. running multiple different campaigns, but I may be misunderstanding exactly what info is being shared. It's possible advertisers are able to match the Google profiles to specific unique identities and thus are sharing much more than just the info they're collecting directly from their ads.
I'd imagine they are responsible too, not just alone, and that Google is a much more attractive target for GDPR enforcement both because they're larger, have more money, are more visible, but also because they're directly facilitating the "different advertisers" sharing that info.
If Google ceases to provide them the means of readily sharing info then all of those entities will no longer be violating the GDPR, in the scenario anyways.
I would guess that yes, they're all receiving – _from Google_ – the "same profile" but they also are collecting additional info that they can then share with each other and, because they can match profiles exactly, they can access each other's info about specific people.
> Wouldn't privacy advocates consider the sending of the profiles at all an issue?
I'd imagine that the profile Google has and shares is by itself fairly anodyne, but I could be (very) wrong about that. The problem seems to be more (if not entirely) that different advertisers can share info using a common profile ID.
I'd imagine that even a single advertiser would be able to perform a similar 'attack' by, e.g. running multiple different campaigns, but I may be misunderstanding exactly what info is being shared. It's possible advertisers are able to match the Google profiles to specific unique identities and thus are sharing much more than just the info they're collecting directly from their ads.