Inconsistent text scaling in web views on iPhone Duo

On iPad, text in a web view is always rendered at the same font size regardless of device orientation, sidebar presence, and window resizing. The text simply reflows according to the available space, as you would expect.

In comparison, there appears to be a bug in iPhone Duo (or the Duo simulator) that causes web views to scale inconsistently depending on device orientation, presense/absence of the sidebar, and inner vs. outer screens. For example, showing and hiding the sidebar causes text in a web view to be rendered at different sizes rather than reflowing the text. Likewise, switching between portrait and landscape orientations causes text to be rendered at different sizes rather than reflowing.

This occurs with the modern WebPage APIs introduced in iOS 26 as well as the older WKWebView APIs.

Is this a known bug on the iPhone Duo? Is it just a simulator problem? Are there any recommended workarounds?

Here's a quick example:

import SwiftUI
import WebKit

struct ContentView: View {
    let webPage = WebPage()
    
    var body: some View {
        NavigationStack {
            WebView(webPage)
                
        }
        .task {
            webPage.load(html: """
                <!DOCTYPE html>
                <html lang="en">
                <head>
                <meta charset="utf-8">
                <title>Test page</title>
                </head>
                <body>
                <h1>This is a title</h1>
                <p>This is a paragraph.</p>
                </body>
                </html>
                """
            )
        }
    }
}