Tapstream, which reported the rejections’ occurrence on Friday, explains that the IDFA today supports a variety of tracking opportunities beyond advertising, though that is the typical case. Publishers are the only ones who are supposed to access the IDFA, not advertisers, Tapstream says. But because ad networks charge advertisers based on installs that are run by end users, the advertiser passes the identifier to the ad network for tracking purposes.
However, many analytics and optimization services also use this identifier, including Mixpanel. Some apps integrated with Mixpanel are also now being rejected. A full rejection letter, posted here, has Apple telling the app developer that: “We found your app uses the iOS Advertising Identifier but does not include ad functionality. This does not comply with the terms of the iOS Developer Program License Agreement, as required by the App Store Review Guidelines.”