UIBarButtonItem getting clipped after a push

I'm attempting to use an untappable UIBarButtonItem in a NavBar that would display a glyph and use CALayer to show a background shadow. I have noticed that the item displays correctly at startup, however as soon as I push a new viewController the UIBarButtonItem clips. Do any of you know of a way to prevent the clipping that occurs after a push?

thanks, in advance!

At app launch

After push and pop

class ViewController: UIViewController {

    var showBack: Bool

    init(showBack: Bool = false) {
        self.showBack = showBack
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        self.showBack = false
        super.init(coder: coder)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        navigationItem.rightBarButtonItem = barButton
        if !showBack {
            navigationItem.leftBarButtonItem = barButton
        }
    }

    var barButton: UIBarButtonItem {
        let config = UIImage.SymbolConfiguration(pointSize: 30)
        let view: UIImageView = .init(image: UIImage(systemName: "multiply.circle", withConfiguration: config))
        view.layer.shadowColor = UIColor.black.cgColor
        view.layer.shadowRadius = 10
        view.layer.shadowOffset = .zero
        view.layer.shadowOpacity = 1.0
        view.layer.masksToBounds = false

        return .init(customView: view)
    }

    @IBAction func navPush(sender: UIButton) {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let vc = storyboard.instantiateViewController(withIdentifier: "vc") as! ViewController
        vc.showBack = true
        self.navigationController?.pushViewController(vc, animated: true)
    }
}