Application called an interface that was marshalled for a different thread?

using System.Timers;

namespace Pomodoro.Views;

public partial class MainPage : ContentPage
{
    int timeLeft = 60;
    private System.Timers.Timer pTimer;


    public MainPage()
    {
        InitializeComponent();

        pTimer = new(1000)
        {
            Enabled = true,
        };

        pTimer.Elapsed += timerTick;
    }

    private void timerTick(object sender, EventArgs e)
    {
        if (timeLeft > 0)
        {
            timeLeft--;
            TimerDisplay.Text=timeLeft.ToString();
        }
        else
        {
            pTimer.Stop();
        }
    } 
    

    private void OnStartTimerClicked(object sender, EventArgs e)
    {
        pTimer.Start();
    }

    private void OnStopTimerClicked(object sender, EventArgs e)
    {
        pTimer.Stop();
    }
}

<Label
                x:Name="TimerDisplay"
                Text="60"
                SemanticProperties.Description="Display of time remaining"
                FontSize="50"
                HorizontalOptions="Center" />