keyWindow?.bounds.size is nil at first load: Swift iPadOS 13

I am developing an app for iPad for iPadOS 13.

There are two UICollectionViewController one navigates from one cell to another UICollectionViewController. I am using the following code:

I have declared keyWindow at UICollectionView Controller as:

let keyWindow = UIApplication.shared.connectedScenes
    .filter({$0.activationState == .foregroundActive})
    .map({$0 as? UIWindowScene})
    .compactMap({$0})
    .first?.windows
    .filter({$0.isKeyWindow}).first

But on first UICollectionViewController 'keyWindow?.bounds.size' gets printed as nil but on second UICollectionViewController same iPad Simulator 'keyWindow?.bounds.size' it gets printed as 'Optional((768.0, 1024.0))'. I am using the exact same code everywhere.

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
     var sizeArea = CGSize()
     print("UIScreen.main.bounds.size \(UIScreen.main.bounds.size)")
     print(keyWindow?.bounds.size)
     if UIScreen.main.bounds.size == keyWindow?.bounds.size {
     print("UIScreen.main.bounds.size == keyWindow?.bounds.size")
     let spacing = self.view.frame.size.width - 25
     let itemWidth = spacing / 4
     sizeArea = CGSize(width: itemWidth, height: itemWidth)
} else {
     print("else")
     let spacing = self.view.frame.size.width - 20
     let itemWidth = spacing / 3
     sizeArea = CGSize(width: itemWidth, height: itemWidth)
}
}

What I am doing wrong here?