Wpf netframeworkcore 3.1 MVVM visibility

I try to hide an object via the properties of another object I do not know what the problem is, but it does not work

Binding code

<StackPanel Orientation="Horizontal">
    <Grid Margin="25,0,0,0" HorizontalAlignment="Center">
        <TextBlock
            Text="اسم المستخدم" 
            FontWeight="Light"
            FontSize="18"
            Foreground="White"
            Background="Transparent"
            Width="230"
            Opacity="0.5"
            Height="28"
            Visibility="{Binding Path=VisbTbU , Mode=TwoWay}"/>
        <TextBox 
            FontFamily="Helvetica"
            FontWeight="Light"
            FontSize="18"
            HorizontalAlignment="Center"
            Foreground="White"
            Background="Transparent"
            BorderThickness="0"
            Width="235"
            HorizontalContentAlignment="Left"
            Opacity="0.5"
            Height="25"
            Text="{Binding UserLog}"
        />
    </Grid>
    <iconPacks:PackIconMaterial 
        Kind="Account"
        VerticalAlignment="Center"
        HorizontalAlignment="Center"
        Foreground="White"
    />
</StackPanel>

viewmodel code

public VmWinLogin()
{
    VisbTbp = Visibility.Visible;
    VisbTbp = Visibility.Visible;
    UserLog = "";
    UserPass = "";
}

private Visibility _VisbTbU ;

public Visibility VisbTbU
{
    get => _VisbTbU;
    set
    {
        _VisbTbU = value;
       // OnPropertyChanging();
       OnPropertyChanging();
    }
}


private string _UserLog ;

public string UserLog
{
    get => _UserLog .Trim();
    set
    {
        _UserLog = value .Trim();
        OnPropertyChanging();
        if (_UserLog == "")
        {
            VisbTbU = Visibility.Visible;
        }
        else
        {
            VisbTbU = Visibility.Hidden;
        }
    }
}

basemodel code

public event PropertyChangingEventHandler PropertyChanging;

public event PropertyChangedEventHandler PropertyChanged;

[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanging([CallerMemberName] string propertyName = null)
{
    PropertyChanging?.Invoke(this, new PropertyChangingEventArgs(propertyName));
}

What I have tried:

I tried to follow the implementation to make sure the value of the property did not change and I found that it changed, but there is no effect on the object.

Tags: .NET Core, WPF, MVVM