Navigation bar - badge counter as bindable property

I want to add badge counter to the navigation bar like in this tutorial.

https://www.xamboy.com/2018/03/08/adding-badge-to-toolbaritem-in-xamarin-forms/

This works great, but I am not satisfied that they created a method for displaying a badge instead of creating a bindable property "BadgeCounter" for toolbar item. So I decided to create this bindable property on my own.

Here is my code:

ExtendedToolbarItem.cs

using System;
using Todo.Helpers;
using Todo.Views;
using Xamarin.Forms;

namespace Todo.Controls
{
    public class ExtendedToolbarItem : ToolbarItem
    {
        public static readonly BindableProperty BadgeCountProperty =
            BindableProperty.Create(nameof(BadgeCount), typeof(int), typeof(ExtendedToolbarItem), 0, BindingMode.OneWay, propertyChanged: BadgeCountChanged);

        public int BadgeCount
        {
            get => (int)GetValue(BadgeCountProperty);
            set => SetValue(BadgeCountProperty, value);
        }

        private static void BadgeCountChanged(BindableObject bindable, object oldValue, object newValue)
        {
            var control = bindable as ExtendedToolbarItem;
            if (control == null) return;

            DependencyService.Get<IToolbarItemBadge>().SetBadge((Page)control.Parent, control, newValue.ToString(), Color.Red, Color.White);

        }
    }
}

Then in the view

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Todo.Views.TodoItems"
             xmlns:viewModels="clr-namespace:Todo.ViewModels"
             xmlns:controls="clr-namespace:Todo.Controls"
             Title="Things to do!">
    <ContentPage.BindingContext>
        <viewModels:TodoItemsViewModel />
    </ContentPage.BindingContext>
    <ContentPage.ToolbarItems>
        <ToolbarItem Icon="plus.png" Command="{Binding AddItemCommand}"/>
        <controls:ExtendedToolbarItem Icon="email.png" BadgeCount="{Binding UnreadMessages}"/>
    </ContentPage.ToolbarItems>

And in the view model, you have to assign some value for "UnreadMessages".

This works great except for two cases.

I don't know why but when I am changing the orientation of the device (Android) the badge counter disappears. It also disappears when I am navigating back. It could be great if someone helps me solve this issue because that would a fantastic way to create a badge counter in Xamarin Forms - currently, there is no way to create it without creating a custom navbar.