Shell navigation to child page and back repeatedly causes blank page on iOS

### Description

When navigating from a Shell tab's root page to a child page and back using the Shell back button, repeating this action several times causes the page to go blank. The content disappears but the Shell chrome (tabs, navigation bar) remains visible.

This is reproducible on iOS 26.4.2 (iPhone 13, iPhone 15 Pro) with both .NET 9 and .NET 10. It is not reproducible on Android or on iOS 15.8.7 (iPhone 7). Navigating with animate=false also does not reproduce the issue.

### Steps to Reproduce

1. Run the app on an iOS device running iOS 26.4.2 (tested on iPhone 13 and iPhone 15 Pro)
2. On the *Home* tab, press the *Go to child page* button
3. Press the Shell back navigation button to return to the Home tab root page
4. Rapidly and repeatedly alternate between the *Go to child* page button and the Shell back button — place one finger on each and tap as fast as possible
5. After several rapid back-and-forth navigations, the page goes blank

**Note:** On the *Other* tab, navigation to the child page uses *animate=false* and the issue cannot be reproduced.

### Link to public reproduction project repository

https://github.com/aalsamoht/ReproBranches/tree/maui/blank-page

### Version with bug

10.0.50

### Is this a regression from previous behavior?

No, this is something new

### Last version that worked well

_No response_

### Affected platforms

iOS

### Affected platform versions

iOS 26.4.2

### Did you find any workaround?

Navigating with animate=false also does not reproduce the issue. Replace `await Shell.Current.GoToAsync($"OtherPageChild");` with `await Shell.Current.GoToAsync($"OtherPageChild", false);`

### Relevant log output

```shell

```