Use PiCamera V2 is surprisengly working without picamera module and using OpenCV in python

Question

I was convinced that in order to use the picamera V2 with openCV I needed to pass by picamera module in python or libraries such as raspicam in C++. However today I saw the following code working in a Raspberry Pi 4 with Raspbian Buster, which left me confused..

import cv2
import numpy as np

cap = cv2.VideoCapture(0, cv2.CAP_V4L)
if not cap.isOpened():
    raise IOError("Error")
while True:
    ret, frame = cap.read()
    filename = "img.jpg"
    cv2.imwrite(filename, frame)
    cap.release()
    break

Has this changed lately? Just curious..