In the two years since Apple released Safari’s Intelligent Tracking Prevention feature that keeps websites from tracking users around the web, it looks to have almost totally eliminated the ability for advertisers to market to specific demographics. A new report from The Information dives into how Apple’s offensive against ads has made things more difficult for advertisers while aiming for greater user privacy.

Executives in the online publishing industry speaking with The Information say that Apple has been “stunningly effective” with its goal of Intelligent Tracking Prevention stopping websites from knowing what users are doing on the web. One of the results of this over the last two years is that costs for advertisers have dropped significantly for Safari users while they’ve gone up for Chrome.

While that might sound like a positive thing for advertisers, the reason the price for Safari ads has gone down is that they’re less desirable. Because of Intelligent Tracking Prevention (ITP), marketers can’t focus on specific demographics, for example like those in higher-income brackets.

This has a greater impact in the US than elsewhere since over 50% of mobile browsing happens on Safari. And while users can opt to turn off Intelligent Tracking Prevention, data shows that most don’t.

Notably, another consequence of Safari’s ITP is that competitors have benefitted.

As for ad firms, one called Criteo says that it has lost as much as $25 million due to ITP. That was for the fourth quarter of 2017, so it’s possible that loss has increased.

However, from another perspective, another executive in the industry thinks marketers need to evolve to target the desired demographics.

Check out the full report from The Information here.