how to make a screen recorder in Python

I want a screen recorder. I thought of making my own.

I checked the internet and found : https://www.thepythoncode.com/code/make-screen-recorder-python

The Code:

import cv2
import numpy as np
import pyautogui

# display screen resolution, get it from your OS settings
SCREEN_SIZE = (1366, 768)
# define the codec
fourcc = cv2.VideoWriter_fourcc(*"XVID")
# create the video write object
out = cv2.VideoWriter("output.avi", fourcc, 30.0, (SCREEN_SIZE))

while True:
    # make a screenshot
    img = pyautogui.screenshot()
    # img = pyautogui.screenshot(region=(0, 0, 300, 400))
    # convert these pixels to a proper numpy array to work with OpenCV
    frame = np.array(img)
    # convert colors from BGR to RGB
    frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
    # write the frame
    out.write(frame)
    # show the frame
    cv2.imshow("screenshot", frame)
    # if the user clicks q, it exits
    if cv2.waitKey(1) == ord("q"):
        break

# make sure everything is closed when exited
cv2.destroyAllWindows()
out.release()

The Problem:

When I run this, this works good. But it has a random speed after output. The fps is 30 but when I record for 1 minute, the video is 5 seconds or 10 minutes (random).

How do I make this recorder give output in 30 fps with the correct speed.

Thanks in advance.