This is a regular "crash" for me on iOS in Spain. When it happens I consider myself extremely lucky that the app automatically restarts and doesn't leave me having to force restart my iPad or reinstall the game. Worse "crashes" are when the screen turns completely black or white, and stays that way............forever, with no on screen escape.
Nordeus support will blame the ad providers.
And the ad providers are safely uncontactable.
You can report it to support if you know which advert is causing the problem and perhaps, perhaps they can get the providers to stop showing the ad.