Input Validation applied for {x:Bind} but not {Binding}

[omnilogix]

Describe the bug

When using InputValidation, the validation does not get applied to bindings of type {Binding}, but does for {x:Bind}

Steps to reproduce the bug

Run attached solution

Reunion.zip

Xaml:

    <Grid x:Name="_Grid">
        <Grid.Resources>
            <local:MainWindowViewModel x:Name="VM" />
        </Grid.Resources>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
            <TextBox InputValidationKind="Inline" Header="Test1" Text="{x:Bind VM.Test1, Mode=TwoWay}" HorizontalAlignment="Left" Width="200" />
            <TextBox InputValidationKind="Inline" Header="Test2" Text="{Binding VM.Test2, Mode=TwoWay}" HorizontalAlignment="Left" Width="200" />
        </StackPanel>
    </Grid>

Expected behavior

Correct validation regardless of binding type

Screenshots

Version Info

NuGet package version:

Windows app type:

UWP	Win32
	Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context

After an invalid input is made, entering valid data and tabbing away does not clear the error
Also note misalignment issue documented here: #4640 (comment)
InputValidation seems to have many issues related to consistent application across controls, and functionality like ErrorTemplate, error positioning, etc.

[omnilogix]

Please move this to the ProjectReunion repo

[StephenLPeters]

Please move this to the ProjectReunion repo

Why do you want this moved? it seems likely a winui issue.

[omnilogix]

Because I keep getting confused what belongs to WinUI 3 / Project Reunion / Windows Toolkit... ;)
If it belongs here, great!

[omikhailov]

AFAIK, this is by design

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[omnilogix]

Any progress on this item?

[michael-hawker]

Tied to Parent issue: #179