The crash will be fixed by updating Firebase or Crashlytics. You can find full solution from here: https://stackoverflow.com/a/78122992/3275012

Have you found the solution @LK00001? This is happening on my app in iPad Pro (12.9-inch, 3rd generation), iOS 15.7.0 as well. Here is the logs: Fatal Exception: NSInternalInconsistencyException -[UINSUIKitBackgroundingController _updateAppWideBackgroundStateSlammingNotifyingDelegate:]: Called off the main thread.

Same issue for me(Uzbekistan)