google-fonts-proxy-enabler.php

<?php
/**
 * Plugin Name: Google Font Proxy Enabler
 * Plugin URI:
 * Description: Get Google Fonts from a proxy server
 * Author: Jörn Schönyan
 * Author URI: https://ifdata.de
 * Version: 1.0
 * License: GPL v2.0
 */

/** This plugin is based on ideas from https://github.com/hzxie/Google-Font-Fix - Thanks Haozhe! */

define('GFF_PLUGIN_PATH', plugin_dir_path(__FILE__));

function google_apis_fix($buffer) {
    return preg_replace('|(https*:)*//(.*).googleapis.com/|', 'https://your.proxy/fgap_mirror/', $buffer);
}

function gff_buffer_start() {
    ob_start("google_apis_fix");
}

function gff_buffer_end() {
    while ( ob_get_level() > 0 ) {
        ob_end_flush();
    }
}
add_action('init', 'gff_buffer_start');
add_action('shutdown', 'gff_buffer_end');

Set up a proxy for Google Fonts like this: https://www.haotoday.com/use-apache-to-setup-a-reverse-proxy-for-google-fonts-in-wordpress/