how to disable auto JPG compression when uploading

can’t figure out how to disable automatic JPG compression when uploading images.

Have searched internet, all solutions were to add this to child theme functions.php

function jpeg_quality_callback($arg) { return (int)100; } add_filter(‘jpeg_quality’, ‘jpeg_quality_callback’);

All with no lcuk, it does not change anything. If i test it by uploading image and then when i download then same image from website and compare it to original on disk the size of uploaded image is smaller which means it is still compressing JPGs on upload.

I have reverted to default theme to find out it does not effect anything, it still does compress no matter what theme so it must be doing WP itself.

Anybody with half decent WP knowledge can help?