Memory leak on Popup with ItemsControl and UserControl with empty Binding

[Arthur-Camatti]

Describe the bug

When having a Popup with an ItemsControl that uses a UserControl as DataTemplate, reopening the popup creates new instances of the UserControl and keeps the past ones on memory, never disposing of them. Removing the DataContext="{Binding}" from the xaml solves the leak.

The output console also prints [Binding]Error in binding to 'AvaloniaMemLeak.Controls.DropdownPackageControl'.'DataContext': 'Null value in expression '{empty}' at ''.'(DropdownPackageControl #...) every time for each new UserControl instance, I'm not sure why.

To Reproduce

Create a Window with a Xaml like so

<Button x:Name="PART_footer_selectButton"
        Padding="7"
        Background="Blue"
        HorizontalAlignment="Center"
        VerticalAlignment="Center">
    Press me
</Button>

<Popup x:Name="PART_footer_selectPopup"
       IsLightDismissEnabled="True"
       PlacementTarget="{Binding #PART_footer_selectButton}">
    <ScrollViewer Background="Yellow">
        <ItemsControl ItemsSource="{Binding PackageViewModels, Mode=OneWay}"
                      Padding="1"
                      Margin="1" x:CompileBindings="True">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Spacing="1"/>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ItemsControl.ItemTemplate>
                <DataTemplate DataType="vm:PackageViewModel">
                    <my:DropdownPackageControl x:DataType="vm:PackageViewModel"
                                               DataContext="{Binding}"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </ScrollViewer>
</Popup>

and bind the button's Click to the popup's Open on the code-behind. Open and close the popup many times and then take a snapshot of the heap using Visual Studio and search for "DropdownPackageControl". There will be many more instances than the 5 ones expected:

If you remove the DataContext="{Binding}" piece from the DataTemplate, the object count does not increase. Not sure if it replaces the old instances or caches them.

Expected behavior

Using DataContext={Binding} on a ItemsControl expected to not keep past UserControl instances on memory and thus cause no memory leak.

Avalonia version

11.0.10

OS

Windows

Additional context

Repro repo: https://github.com/Arthur-Camatti/AvalPopupMemLeak.

Periodic GC.Collect() calls have no effect.
Using .NET 8.0.
Same behavior with Avalonia 11.1.0-beta2.
Same behavior with ReactiveUserControl instead of UserControl.
Haven't tested default Avalonia controls with {Binding}.
Tested with and without x:CompileBindings.
Have confirmed that every Control under the Popup's logical tree is the same instance, except the UserControl (maybe also the ContentPresenter?). I might be mistaken though.