Facebook again warns that Apple privacy changes are hurting business

Facebook says that Apple's changes to how apps track users on iOS is harming its business. 

Graham Mudd, Facebook's vice president of product marketing, said Wednesday in a blog post that underreported metrics resulting from Apple's privacy changes have made it more difficult for businesses to measure ad campaigns on Facebook's platform. 

"Our estimate is that in aggregate we are underreporting iOS web conversions by approximately 15%; however there is a broad range for individual advertisers," Mudd said. He added that Facebook is also expecting "increased headwinds from platform changes, notably the recent iOS updates, to have a greater impact in the third quarter compared to the second quarter."

In July, Apple rolled out an update to its iOS software that powers iPhones, requiring app developers to outright ask users for permission to be tracked across Apple's App Store and the internet. Facebook, which makes billions of dollars from targeted online advertising, was outspoken against the change. Facebook CEO Mark Zuckerberg said Apple's demand would hurt small businesses and raise advertising costs across the internet.

The dispute underscores a fundamental difference between the tech giants: how they make money. Apple sells smartphones and laptops and takes a cut of fees charged to app developers. Facebook sells ads that it can target precisely based on the trove of data it collects on its 2.8 billion monthly users.

Facebook issued a similar warning during its earnings report in July, saying it expected the iOS change to impact its ad business for the third quarter.  

Apple didn't immediately respond to a request for comment.