animation stack change after size class changes

gistfile1.swift

import SwiftUI

final class SizeClassNotifier: ObservableObject {
    
    @Published var currentSizeClass: UserInterfaceSizeClass =
        .compact
    
    func updateSizeClass(sizeClass: UserInterfaceSizeClass?) {
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
            self.currentSizeClass = sizeClass ?? .compact
        }
    }
}

struct AdaptiveStackView: View {
    
    @Environment(\.verticalSizeClass) var sizeClass
    @ObservedObject var sizeClassNotifier: SizeClassNotifier = .init()
    
    @Namespace var animation
    
    var body: some View {
        VStack {
            if sizeClassNotifier.currentSizeClass == .compact {
                VStack {
                    Text("Hello")
                        .matchedGeometryEffect(id: "hello", in: animation)
                    Text("World")
                        .matchedGeometryEffect(id: "world", in: animation)
                }
                
            } else {
                HStack {
                    Text("Hello")
                        .matchedGeometryEffect(id: "hello", in: animation)
                    Text("World")
                        .matchedGeometryEffect(id: "world", in: animation)
                }
            }
        }
        .animation(.linear)
        .onChange(of: sizeClass ?? .compact, perform: { value in
            self.sizeClassNotifier.updateSizeClass(sizeClass: value)
        })
    }
}

struct AdaptiveStackView_Previews: PreviewProvider {
    static var previews: some View {
        AdaptiveStackView()
    }
}