Official comment
Apple has a Vendor identifier that identifies a device in the same way to each app vendor. That is what we are using with Apple stuff. Android doesn't have anything like this so we are having to use an installation id instead.
The changing of this value is something that happens when you install using an APK vs updating from an App Store. The Android versions are actually available in the Amazon App Store so updating from there won't change the internal ID that we use to track devices.
The Amazon App Store (since Google Play Store can't be installed) will be the preferred method of installation for certain DJI devices moving forward. There seem to be some devices that will be hard for though.
If this does become a problem we will likely add something to deal with it.
PS - we have reset your devices.