Not surprising Early analysis suggests that following the release of Apple iOS 14.5 on April 26, the vast majority of users are keeping in-app tracking disabled. A mere 4 percent of users are allowing apps to track their activity across other companies' apps and websites. Because honestly, if given the choice, who would say yes?

Apple's move to bolster user privacy by forcing apps to request to track users' data has been at the center of a dispute between the iPhone-maker and Facebook. The social network has been critical of Apple's App Tracking Transparency changes in iOS 14, going as far as publishing newspaper ads speaking out against the move.

Facebook is even said to be preparing to go to court to protect its interests, meaning Apple could have another high profile legal battle on its hands.

Analysis from app analytics firm Flurry indicates that Facebook has good reason to be concerned. According to early sampling of 2.5 million users in the U.S., 96 percent have opted to disable app tracking in iOS 14.5. This figure isn't increasing, either, but has instead been relatively stable since launch week.

Worldwide data is slightly higher, with some 12 percent of users allowing app tracking on their devices.

Although it's early days, the data indicates that the personalized ad market has a big challenge on its hands following the release of iOS 14.5.

You can disable in-app tracking altogether on your iPhone (or iPad) by launching the Settings app, choosing Privacy, selecting Tracking, and disabling "Allow Apps to Request to Track."