Serve WEBP format from JetPack CDN using WP Rocket buffer output [WordPress]

fetch_webp_from_jetpack_cdn_via_wprocket_buffer.php

//For testing purposes
if (!is_user_logged_in() ) {
    function sz_wprocket_filter_buffer($buffer)
    {
        $jetpack_cdn = 'https://i1.wp.com/';
        $buffer = preg_replace('/((http|https)\:\/\/)(([^\"|^\)|^\']*?)(?:.jpg|.jpeg|.png))/im', $jetpack_cdn . '${3}', $buffer);
        return $buffer;
    }

    add_filter('rocket_buffer', 'sz_wprocket_filter_buffer', 10);
}