.preferredColorScheme(nil) visual bug when switching to system light / dark more

I have a simple settings view for my MacOS app with a segmented picker for setting the light/dark/automatic(system) mode. It works just fine when switching between the dark and light modes, but when I set it to system (.preferredColorScheme(nil)), it looks like it initially colors half the app light and half dark. If I click again or click away, it all sets to the proper system mode. But it looks broken on initial selection:

Here's the picker from my settings view:

Picker("",selection: $userSettings.appearance) {
    Text("Automatic").tag(0)
    Text("Dark").tag(1)
    Text("Light").tag(2)
}
.pickerStyle(SegmentedPickerStyle())
.labelsHidden()

It sets a value in my UserSettings:

class UserSettings: ObservableObject {
    @AppStorage("appearance") var appearance: Int = 0
    
    var selectedColorScheme: ColorScheme? {
        switch appearance {
        case 1:
            return .dark
        case 2:
            return .light
        default:
            return nil
        }
    }
    //other stuff
}

And then I set the actual mode on the outer-most view in my ContentView:

struct ContentView: View {
    @StateObject private var userSettings: UserSettings

    var body: some View {
        NavigationSplitView {
        //stuff
        } detail: {
        //stuff
        }
        .preferredColorScheme(userSettings.selectedColorScheme)
}

I've also tried to set the .preferredColorScheme in the main app struct but it doesn't make a difference.

From the last comment in this thread, I also got a sense that this could be a SwiftUI bug.