Concentric rectangle shape

Yesterday on Explore the biggest updates from WWDC Curt Clifton shared .background(.tint, in: .rect(corner: .containerConcentric)). XCode26 beta 3 don‘t recognize it. how when we can use it??

It should be .background(.tint, in: .rect(corners: .concentric)). Please test on Xcode 26 Beta 4.

It seems like this only works when the shape or image is close to the edge of the screen. for example this works:

var body: some View {

    VStack{
        Spacer()
        
        Color.yellow
            .padding()
            .background(Color.red, in: .rect(corners: .concentric))
            .padding(20)
            .frame(height: 300)
    }
    .ignoresSafeArea()
  
}

but this does not:

var body: some View {

    VStack{

        Color.yellow
            .padding()
            .background(Color.red, in: .rect(corners: .concentric))
            .padding(20)
            .frame(height: 300)
    }
    .ignoresSafeArea()
  
}

Is this the intended behavior or is this a bug?

Concentric rectangle shape
 
 
Q