How to bind from a VM to properties of inner controls of a custom control in .NET MAUI

I am trying to make a custom checkbox.

I created the dependency property IsChecked, but I cannot bind to it from a VM.

In the control I have

<ContentView xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
             x:Class="PaperScoreTracker.Controls.PaperCheckBox"
             x:Name="this">

    <HorizontalStackLayout BindingContext="{x:Reference this}">
        <CheckBox x:Name="Part_CheckBox"
                  IsChecked="{Binding IsChecked}"/>
        <Label FontSize="20"
               Text="{Binding Text}"/>
    </HorizontalStackLayout>
    
</ContentView>

and then in the code behind I have

public partial class PaperCheckBox : ContentView
{
    public static readonly BindableProperty IsCheckedProperty = BindableProperty.Create(nameof(IsChecked), typeof(bool), typeof(PaperCheckBox), false);
    public static readonly BindableProperty TextProperty = BindableProperty.Create(nameof(Text), typeof(string), typeof(PaperCheckBox), string.Empty);

    public bool IsChecked
    {
        get => (bool)GetValue(IsCheckedProperty);
        set => SetValue(IsCheckedProperty, value);
    }

    public string Text
    {
        get => (string)GetValue(TextProperty);
        set => SetValue(TextProperty, value);
    }

    public PaperCheckBox()
    {
        InitializeComponent();
    }
}

In the actual page I have

<controls:PaperCheckBox Grid.Row="1" Grid.Column="0"
                        IsChecked="{Binding ReverseScoring}"
                        Text="Reverse scoring"/>

and I have a VM for this page with the ReverseScoring observable property.

The problem is that ReverseScoring in the VM does no change when I check the checkbox in the UI.

What's weird is that the setting of a constant value works. I did Text="Reverse scoring" and in the UI the text is correct.

I made another custom button and I did the same thing but with a property of type Command. That one works. The command is forwarded from the control to the VM. Just the simple properties are not.

The Bindable Propertie's Binding Mode needs to be set to TwoWay in order to propagate the changes to your viewmodel. Learn more...

public static readonly BindableProperty IsCheckedProperty = BindableProperty.Create(
nameof(IsChecked), 
typeof(bool), 
typeof(PaperCheckBox), 
false,
BindingMode.TwoWay);

public static readonly BindableProperty TextProperty = BindableProperty.Create(
nameof(Text), 
typeof(string), 
typeof(PaperCheckBox), 
string.Empty,BindingMode.TwoWay);