"cordova") return false on some iOS 11 devices

Inside platform.ready() callback I check whether this is a mobile device with cordova or if it is a local ionic serve runtime.
This works fine on most devices but on some iOS 11 devices“cordova”) returns false.
platform.platforms returns a array without corodova (but with ios).

If the user uninstalls the app and reinstall it, the app works fine for some time.
After a while the same issue reappears.

Anyone having the same problem?

See: If ('ios')) not returning true on iOS