Sheet view not showing on devices running below iOS 16 beta

I have shared my app via testflight with a couple of friends, trying to test out some new sheet views. I have Xcode 14 installed and on my iOS 16 beta iPhone it works fine. On all other iPhone (using iOS 15) the sheet views are simply not showing up. Any ideas why? I'm trying to figure out if its beta related (bug) or something I'm missing. Here the code:

@State private var showSheet: Bool = true

....

MainView()
        .sheet(isPresented: $showSheet, content: {
            VStack {
                Text("Willkommen!")
                    .font(.largeTitle)
                Text("Lass uns gemeinsam diese Insel entdecken")
                    .foregroundColor(.secondary)
                VideoPlayer(player: AVPlayer(url:  Bundle.main.url(forResource: "video", withExtension: "mp4")!))
                    .frame(height: 220)
            }
        })