identifierForVendor

h ttps://developer.apple.com/documentation/uikit/uidevice/1620059-identifierforvendor

The value of this property is the same for apps that come from the same vendor running on the same device. A different value is returned for apps on the same device that come from different vendors, and for apps on different devices regardless of vendor.

Normally, the vendor is determined by data provided by the App Store. If the app was not installed from the app store (such as enterprise apps and apps still in development), then a vendor identifier is calculated based on the app’s bundle ID. The bundle ID is assumed to be in reverse-DNS format.

So, you have an id from the appStore and a different one in debug build.