主要原因是在iOS 15上，隐私弹框经常性无法弹出，审核人员看不到所以被拒。

被拒邮件如下：

We're looking forward to completing our review, but we need more information to continue. Your app uses the AppTrackingTransparency framework, but we are unable to locate the App Tracking Transparency permission request when reviewed on iOS 15.1.

Since you indicated in App Store Connect that you collect data in order to track the user, we need to confirm that App Tracking Transparency has been correctly implemented. 

Next Steps

Please explain where we can find the App Tracking Transparency permission request in your app. The request should appear before any data is collected that could be used to track the user.

If your app does not track users, please update your app privacy information in App Store Connect. You must have the Account Holder or Admin role to update app privacy information.

If you've implemented App Tracking Transparency but the permission request is not appearing on devices running the latest OS, please review the available documentation and confirm App Tracking Transparency has been correctly implemented.

Resources 

- Tracking is linking data collected from your app with third-party data for advertising purposes, or sharing the collected data with a data broker. Learn more about tracking. 
- See Frequently Asked Questions about the new requirements for apps that track users.
- Review developer documentation for App Tracking Transparency.



Since your App Store Connect status is Metadata Rejected, we do NOT require a new binary. To revise the metadata, visit App Store Connect to select your app and revise the desired metadata values. Once you’ve completed all changes, reply to this message in Resolution Center and we will continue the review.

网上一些延迟N秒后的解决方法也存在问题，正确解决方案为如下

监听UIApplicationDidBecomeActiveNotification通知，在对应回调内调用获取授权方法

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];


- (void)didBecomeActive {
    if (@available(iOS 14.0, *)) {
        [ATTrackingManager requestTrackingAuthorizationWithCompletionHandler:^(ATTrackingManagerAuthorizationStatus status) {
            
        }];
    }
}

此问题应该是iOS 15系统问题，以上方案可完美解决，目前已过审。