Apple made accessing a devices IDFA (device fingerprint) a permissioned resource. Needless to say it is not a popular permission to grant.
Cross-app activity can't be tracked without this permission. So if you see an ad for a product on facebook, then you pop over to Safari, search for the product, and purchase it, facebook can't attribute that sale to that ad.
The consequence of this is that goal attribution (like sales) for ads is harder, so FBs models can't learn as well who would be interested in the products. You'll see less relevant ads and companies' cost of customer acquisition will go up.
It's easy to imagine a world with less effective ad targeting since most media doesn't have effective targeting. Think pharmaceutical commercials on TV.
My own bias: I run a niche D2C brand whose business model got wrecked by this change!
Facebook has never been able to track the user that pops over to Safari to do the final sale. Even before IDFA went away since that is not sent with requests made in Safari.
Apple disallowed third party cookies (like all other browsers) so now your website with Facebook embedded can only tell Facebook "I got a visitor" and Facebook has no data on who that user is (since they look to be logged out). Before third-party cookie blocking was a thing, Facebook could track users if they were logged in on the web, and thus could potentially attribute the sale to an ad that was shown in Facebook itself.
If the user clicked the link in Facebook for your ad, then popped over to Safari by clicking the "open in Safari" button then Facebook can continue to track that because they saw the final click and can add query parameters on the other end that you can send to Facebook upon checkout completion.
What Facebook can't track now is when a user installs Candy Crush, Quit Smoking app, and Instagram... thereby limiting what ads it can show a user in Instagram to just the behavioral data they get from Instagram, instead of knowing the user also has Candy Crush and a Quick Smoking app (and thus would likely be interested in quick games and cessation of smoking stuff).
1. You're on a website about pets, which has FB code on it: Facebook can't link that activity to your account anymore, which means they'll have less accurate info about you that might be relevant to advertisers.
2. You see an ad on Facebook and then go to that website to make a purchase -> FB can't link that purchase to your profile and as such a) can't tell the advertiser whether their ads are effective b) can't use that data to optimize the campaign for users like you who might also be likely to buy.
1. Is due to third-party cookie disablement that has been made by all browsers. Since Facebook's JavaScript is a third party site it no longer gets cookies as if you were logged in, so they can't track you. This is not Apple specific.
2. Within the Facebook app if you click a link and make a purchase they can absolutely still track you. If you click a link and open it in Safari, they can still track you.
If however you see an ad on Facebook and search for it in your browser without clicking any links then Facebook can't track you, do to third party cookies being disabled.
that’s a pretty good description. a lot of people are not old enough to remember having to watch ads that were uninteresting and not applicable to them. so people will see more unrelated junk on their newsfeed
I’m also old enough to remember when you needed to hire a private investigator to keep tabs on someone’s movements, but now anyone can easily track anyone else using their flashlight app and games on their phone. You can even track the President of the USA
They probably want access to all your contacts with their phone numbers and email so they can build better graphs about your social circle and build shadow profiles on all your friends.
If you go further you can probably find hundreds more interesting data points like constant location tracking or full access to any media file mixed with face recognition software.
In short: Your phone is a goldmine of information not only on yourself but anyone you know.
Even using accelerometer data to gather movements' data points and be able to retrace steps to have a rough localisation. It's "tracking technology" in the most literal sense.
