SCNNode into SKScene is deformed when hit an object

Into a SKScene, I add a SCNSphere as a child of SKShapeNode, as depicted below. When the sphere hit another node (the fence in the example) the sphere is deformed as it were elastic.

I didn't found any information about elastic properties.

Someone know a way to avoid the deformation?

import SwiftUI
import SpriteKit
import SceneKit
@main struct MyApp: App
{
	var body: some Scene
	{
		WindowGroup {SpriteView(scene: GameSceneSK(size: UIScreen.main.bounds.size))}
	}
}
class GameSceneSK: SKScene
{
	override func sceneDidLoad() {
		var fencePoints = [
			CGPoint(x: 300, y: 0), CGPoint(x: 300, y: 400), CGPoint(x: 0, y: 400)
		]
		let fence = SKShapeNode(points: &fencePoints,
								count: fencePoints.count)
		fence.physicsBody = SKPhysicsBody(edgeChainFrom: fence.path!)
		addChild(fence)
		let sphereGeometry = SCNSphere(radius: 20)
		let sphereNode = SCNNode(geometry: sphereGeometry)
		let sphereScnScene = SCNScene()
		sphereScnScene.rootNode.addChildNode(sphereNode)
		let ball3D = SK3DNode(viewportSize: CGSize(width: 40,
												   height: 40))
		ball3D.scnScene = sphereScnScene
		let ball = SKShapeNode(circleOfRadius: 20)
		ball.physicsBody = SKPhysicsBody(circleOfRadius: 20)
		ball.addChild(ball3D)
		physicsWorld.gravity = CGVector(dx: 0.2, dy: 0.2)
		addChild(ball)
	}
}