plugin development – Resized images get 10 times bigger after upload

I compress my images before uploading, so don’t want WordPress to reduce quality. I’ve used the following code in my functions.php for that:

function av_return_100(){ return 100; }
add_filter('jpeg_quality', 'av_return_100');
add_filter('wp_editor_set_quality', 'av_return_100');

The issue is now the resized images for the other sizes getting up to 10 times bigger. The original image is remaining the same size, however.

How can I fix this issue, so that the resized images do not get bigger than the original image. Thanks!