Make images added through divi (or other shortcode-based page builder) responsive in multisite

responsive-divi.php

// Make DIVI images responsive by adding srcset

function make_divi_img_responsive( $output, $tag ) {
    if ( 'et_pb_image' !== $tag ) {
        return $output;
    }
    if ( ! preg_match_all( '/<img [^>]+>/', $output, $images ) ) {
        return $output;
    }
    foreach ( $images as $image ) {
        if ( ! preg_match( '/<img(.*?)src=("|\'|)(.*?)("|\'| )(.*?)>/s', $image[0], $matches ) ) {
            return $output;
        }
        $image_url = $matches[3];
        $upload_dir = wp_get_upload_dir();
        $parsed_dir = wp_parse_url( $upload_dir['baseurl'] );
        $image_url = str_replace( $parsed_dir['path'] . '/', '', $image_url );
        $attachment_id = attachment_url_to_postid( $image_url );
        if ( 0 === $attachment_id ) {
            return $output;
        } else {
            $image_meta = wp_get_attachment_metadata( $attachment_id );
            return wp_image_add_srcset_and_sizes( $image[0], $image_meta, $attachment_id );
        }
    }

}
add_filter( 'do_shortcode_tag', 'make_divi_img_responsive', 10, 2 );