Only 4 percent of US iPhone users have agreed to app tracking after iOS 14.5

Facebook's worries about iOS 14.5 might have been justified. Flurry Analytics (owned by Engadget's parent Verizon Media) has determined that just 4 percent of American iPhone users running the new software opted in to app tracking in the first 12 days after it arrived. That opt-in rate climbed to 12 percent worldwide, but it's still clear that most people are turning down the requests when they receive prompts.

The study was a comprehensive one: it followed about 2.5 million daily active users in the US, and 5.3 million worldwide.

While there's no guarantee these rates will stay the same, they help explain why Facebook has attacked Apple's privacy changes since they were announced in 2020. The social network appears poised to lose a large portion of its iOS ad targeting data, and that in turn could hurt the company's all-important ad revenue.

Facebook has positioned iOS 14.5's app tracking prompt as an attack on small businesses, and has even suggested that companies might have to start charging for site access without previous levels of ad personalization. Apple has refused to back down, however, arguing that users deserve choice and transparency. If the Flurry data holds up over time, Apple might have another reason to hold its ground — it'll have strong support from its customers.