How to eliminate errors on serial COM5 reading?

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C#

Hello,
I have this tested code that works.
I am reading the serial port 'COM5' at 9600 Baud Rate, with successful results. The data on this port comes from an arduino board that is reading some other stuff on its I/O pins.
But some results are erroneous. So this is my question. How to eliminate the errors in this serial reading?
View : https://europe1.discourse-cdn.com/arduino/original/4X/e/9/4/e94046a13b95d61da40e4953fedfac9df8a22cb8.png[^]

I have to do either a string trick or to find a specific function inside SerialPort method. Your advise is invaluable.
Thank you.

What I have tried:

using System;
using System.IO.Ports;

namespace ConsoleApplication1
{
    class ArduinoSerialReader
    {
        static void Main(string[] args)
        {
            SerialPort arduinoPort = new SerialPort("COM5", 9600); // Replace "COM3" with the appropriate port name

            try
            {
                arduinoPort.Open(); // Open the serial port
                arduinoPort.DataReceived += new SerialDataReceivedEventHandler(ArduinoPort_DataReceived); // Subscribe to the DataReceived event
                Console.WriteLine("Listening for Arduino data...");

                Console.ReadLine(); // Wait for user input to exit
         
                arduinoPort.Close(); // Close the serial port
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error: " + ex.Message );
            }
        }


        static void ArduinoPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            SerialPort port = (SerialPort)sender;
            string receivedData = port.ReadExisting(); // Read the available data from the serial port

            Console.WriteLine(receivedData);
        }
    }
}