XCode 12 built code reenables idleTimer on iOS 13&14?

I see a weird bug. I have the following code:

Code Block
 func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        application.isIdleTimerDisabled = true
...


However, this has no effect on some iOS devices. This was not the case before when code was built with XCode11.x. Is this a known bug?