Arduino Serial Read Reading more than a byte

I'm having a problem reading serial bytes. If I input A, the code outputs: This just in ... A.

It's correct, but the problem happens when I input more than 1 character.

Input: AAA
Output:

This just in ... A
This just in ... P
This just in ... �

Device: Arduino Nano.
No other pins are connected. Only the cable connects to my PC.

My Baud rate is correct, 9600 -> 9600.
My code, from a simple example. the problem can't be the code.

char receivedChar;
boolean newData = false;

void setup() {
 Serial.begin(9600, SERIAL_8N1);
 Serial.println("<Arduino is ready>");
}

void loop() {
 recvOneChar();
 showNewData();
}

void recvOneChar() {
 if (Serial.available() > 0) {
 receivedChar = Serial.read();
 newData = true;
 }
}

void showNewData() {
 if (newData == true) {
 Serial.print("This just in ... ");
 Serial.println(receivedChar);
 newData = false;
 }
}

I'm sorry it's in Chinese, The value is by following: 9600, 8, None, 1, None.

And this is the advanced settings tab. the default setting.

So I tried to print the character in binary:

char receivedChar;
boolean newData = false;

void setup() {
 Serial.begin(9600, SERIAL_8N2);
 Serial.println("<Arduino is ready>");
}

void loop() {
 recvOneChar();
 showNewData();
}

void recvOneChar() {
 if (Serial.available() > 0) {
 receivedChar = Serial.read();
 newData = true;
 }
}

void showNewData() {
 if (newData == true) {
 Serial.println(receivedChar, BIN);
 newData = false;
 }
}

Input: A
Output: 1000001

Input: AAA
Output:

1000001
1010000
11111111111111111111111111010000

The output gets weirder and weirder the longer my input length is.

I have searched like 100 times on Google and most of them makes me know more what I'm dealing with, but none of them solves my problem. I asked ChatGPT, it didn't provide any solution more than check your baud rate. I even tried using the old IDE, So here I am, finally asking a question here.

I was randomly changing some settings and it worked. I changed the clock divider from 1 to 2, now I can read characters properly.