You may create an information popup prior to requesting the App Tracking Transparency authorization. When the user closes the popup, you request for authorization. In this way, you can be assured that the application state is UIApplicationStateActive. Adding a delay as others suggested may not work if for some reason the application state is not active when the delay ends e.g. device is slow which causes the delay to expire while app is still on the loading screen.

Same issue on 34" Viewsonic VA3456 using HDMI on Mac Mini 2014 with Big Sur 11.6 and Catalina 10.5.7. By trial and error I got it to work with SwitchResX using 3440x1440@50Hz. Even if I entered 50Hz, SwitchResX was changing it to 45 or 30. So, I had to try multiple times. Using other frequencies other than 50Hz messed up my display (blurry lines) that I had to use recovery to delete /Library/Displays/Contents/Resources/Overrides/ as mentioned in the SwitchResX FAQ.

To clear the cache, delete this folder: ~/Library/Containers/{CFBundleName} To delete the app, right-click on the app icon when the app is launched, select Options->Show in Finder. Delete the highlighted .app file.

I can see the requirements for 13" iPad from the link you provided.