Location tracking data is not any different than the sort of location logging that is already done by the wireless provider. Security researchers found that the sensitive data is stored unencrypted and unprotected, and that it is stored on every PC you sync your iOS device with. The data can be easily accessed and provides data on everywhere your 3G iOS device has been since iOS 4 was released. There is also a possibility such information can be accessed remotely with custom crafted malware, and then sold on the black market.”]
Source: https://www.csoonline.com/article/2128139/why-is-your-iphone-or-ipad-spying-on-you-.html