Getting rid of SwiftUI ScrollView top padding

I just can't seem to get rid of the ~6 height padding(?) at the top of ScrollView. I've tried setting padding to 0 on both the ScrollView itself and on it's content. I've tried using SwiftUI-Introspect to get at the content insets, but they appear to already be 0 for the top. I could just use offset(y: -6), but I'd like to understand what is causing the padding. Does anyone know?

var body: some View {
    VStack(spacing: 0) {
        Rectangle()
            .frame(width: UIScreen.main.bounds.width, height: 200)
            .foregroundColor(.blue)
        Rectangle()
            .frame(width: UIScreen.main.bounds.width, height: 200)
            .foregroundColor(.red)
        ScrollView {
            Rectangle()
                .frame(width: UIScreen.main.bounds.width, height: 200)
                .foregroundColor(.black)
        }
    }
}