QApplication: invalid style override 'kvantum' passed, ignoring it

Question

I'm trying to read an image from bytes with Python. I'm using the open-cv library with pipenv on Manjaro. When python runs this line, I get:

QApplication: invalid style override 'kvantum' passed, ignoring it. Available styles: Windows, Fusion".

Do you have any ideas what might cause this issue and how to fix it ? The thing is, I don't think I can change the theme through the library.

Thank you !

That's my code

import numpy as np
import cv2
img = cv2.imdecode(np.frombuffer(img_data, dtype=np.uint8), flags=0)