memory leak when returning result of Observable.ToBinding() from a Markup-Extension

[BinaryCraX]

Describe the bug

Bindings provided by Markup-Extensions which are constructed from Observables using ToBinding are never unsubscribed from, resulting in a memory leak.

To Reproduce

Sample code:
Extension:

internal class TestMarkupExtension : MarkupExtension
{
    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return Observable.Never<string>().ToBinding(); // will never be unsubscribed
    }
}

Usage:

<TextBlock Text="{local:TestMarkup}" />

I created a Demo-Project to demonstrate the issue. Click the "Toggle"-Button multiple times and watch the debug-output. The subscription to the observable in the ViewModel gets disposed properly, but the subsciption to the observable from the MarkupExtension doesn't.

Expected behavior

The subscription should be disposed when the view get's removed.

Avalonia version

11.2.3, 11.0.10

OS

Windows

Additional context

No response

[maxkatz6]

Seems like a duplicate of #5872