Using WKWebKit and Safari on visionOS

I have implemented a custom view that shows a page in WKWebKit:

import SwiftUI
import WebKit

struct WebView: UIViewRepresentable {
    let urlString: String

    func makeUIView(context: Context) -> WKWebView {
        let webView = WKWebView()
        webView.navigationDelegate = context.coordinator
        return webView
    }

    func updateUIView(_ uiView: WKWebView, context: Context) {
        if let url = URL(string: urlString) {
            let request = URLRequest(url: url)
            uiView.load(request)
        }
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    class Coordinator: NSObject, WKNavigationDelegate {
        var parent: WebView

        init(_ parent: WebView) {
            self.parent = parent
        }
    }
}

It works, but it shows a grey button in the upper left with no icon. If I click on that button, nothing happens. But I can see this error message in the Xcode logs:

Trying to convert coordinates between views that are in different UIWindows, which isn't supported. Use convertPoint:fromCoordinateSpace: instead.

What is this button, and how can I get rid of it?

As a second question: I also tried to spawn Safari in a separate window, using this view:

import SafariServices
import SwiftUI

struct SafariView: UIViewControllerRepresentable {
    let url: URL

    func makeUIViewController(context: Context) -> SFSafariViewController {
        return SFSafariViewController(url: url)
    }

    func updateUIViewController(_ uiViewController: SFSafariViewController, context: Context) {
        // No update logic needed for a simple web view
    }
}

This works, but Safari shows up behind the view that is including the Safari view. Instead, I would want Safari to show up in front - or even better: next to my main view (either left or right). Is there a way to do this?