Why do Fontawesome cdn js & main2 js give 403 & 404 errors on server when they worked on localhost in WordPress?

If I’m not mistaking, any fontawesome hosted outside the fontawsome (eg: cloudfare) website in non-official. You have to go through the proper request from the start section on their website https://fontawesome.com/start. Any non-official hosting is prone to problem (eg: legal action, termination of service)

The 4.7 version isn’t the youngest, we’re now at 5.15.3 public and 6.0.0 pro.

It seems you’re trying to load 2 different version and are doing it so without specifying any crossorigin attributes crossorigin="anonymous", which is apparently required.

1. Remove all fontawesome related scritps and style.
2. Go through the proper channel https://fontawesome.com/start and get your CDN from there.
3. Enqueue it with specifying a crossorigin="anonymous" attribute. (see the following snippet).
4. As icons are usually part of the front line, above the fold, it’s a good idea to preload/prefetch them. (see the following snippet).
5. Setup a local fallback, if the CDN isn’t available. (see the following snippet).

Everything has been tested and is working locally and online.

<?php
add_action( 'wp_enqueue_scripts', 'wpso66883439' );

if ( ! function_exists( 'wpso66883439' ) ) {

    function wpso66883439() {

        if ( ! is_admin() ) {

            /**
             * Register then enqueue font_awesome_js.
             * @link https://developer.wordpress.org/reference/functions/wp_register_script/
             * @link https://developer.wordpress.org/reference/functions/wp_enqueue_script/
             * 
             * Check if CDN's url is valid, if not return fallback.
             * @link https://www.php.net/manual/en/function.fopen.php
             * 
             * Add rel='preload prefetch' <link> and required attributes to font_awesome_js.
             * Filters the HTML link tag of an enqueued style & add required attributes.
             * @link https://developer.wordpress.org/reference/hooks/script_loader_tag/
             */
            $url_font_awesome_js = 'https://kit.fontawesome.com/13234810930.js'; //... your CDN's url goes here
            $ver_font_awesome_js = '5.15.3'; //... script current version goes here
            $hnd_font_awesome_js = 'font_awesome_js'; /... script handle

            if ( false !== @fopen( $url_font_awesome_js, 'r' ) ) { //... test CDN and continue if success
                wp_register_script( $hnd_font_awesome_js, $url_font_awesome_js, array(), $ver_font_awesome_js, true ); //... register via CDN
            } else { //... fallback to local if CDN's fail
                wp_register_script( $hnd_font_awesome_js, trailingslashit( get_template_directory_uri() ) . 'assets/js/13234810930.js', array(), $ver_font_awesome_js, true ); //... register via local hosting
            };

            wp_enqueue_script( $hnd_font_awesome_js ); //... enqueue font_awesome_js
            
            add_filter( 'script_loader_tag', 'data_font_awesome_js', 10, 3 );
            if ( ! function_exists( 'data_font_awesome_js' ) ) {
                function data_font_awesome_js( $tag, $handle, $src ) { //... here we catch the <script> tag before it's loaded and we make some changes to it, add the crossorigin="anonymous" and the rel='preload prefetch' <link>
                    if ( 'font_awesome_js' === $handle ) {
                        $tag = str_replace(
                            array(
                                "<script", 
                                "></script>", 
                            ),
                            array(
                                "<link rel='preload prefetch' href='" . esc_url( $src ) . "' as='script' crossorigin='anonymous' /><script", 
                                " crossorigin='anonymous'></script>",
                            ),
                            $tag
                        );
                    };
                    return $tag;
                };
            };
        };
    };
};
?>

Current script is bogus. Request CDN’s script @ https://fontawesome.com/start.