404 error when going to a taxonomy page with a label in Cyrillic, what's wrong?

Question

WordPress

Hello, I have
a question and need help.
There is a permalink structure for a custom post type:

mysite.com/products/term-1/child-term-2/grandchild-term-3/product-name

The problem is that if you set a slug (link label) for terms in Cyrillic, then when you go to the term-1 category, the page opens, and when you go to nested categories, a 404 error occurs.
However, if everything is in Latin, the flight is normal.

Here is the code:

<?php
/*
* Plugin Name: MOD
* Description: DEV
*/

/**
 * Создание произвольного типа записи
 * - register_post_types()
 */
add_action('init', 'register_post_types', 0);
function register_post_types()
{
// тип записи
    register_post_type('mod_services', array(
        'labels' => array('name' => __('Товары')),
        'public' => true,
        'show_in_menu' => true,
        'show_in_rest' => null,
        'rest_base' => null,
        'hierarchical' => false,
        'supports' => array('title', 'editor', 'thumbnail'),
        'has_archive' => true,
        'rewrite' => array('slug' => 'catalog', 'with_front' => false),
        'query_var' => true,
    ));
// таксономия
    register_taxonomy('mod_services_catalog', array('mod_services'), array(
        'labels' => array('name' => __('Категории')),
        'public' => true,
        'hierarchical' => true,
        'rewrite' => array('slug' => 'catalog', 'hierarchical' => true, 'with_front' => false),
        'capabilities' => array(),
        'meta_box_cb' => null,
        'show_admin_column' => false,
        'show_in_rest' => null,
        'rest_base' => null,
    ));
}

/**
 * Изменяем структуру ссылок записей
 * - products_permalink()
 */
add_filter('post_type_link', 'products_permalink', 1, 2);
function products_permalink($permalink, $post)
{
    if (strpos($permalink, 'catalog') === false) return $permalink;
    $terms = get_the_terms($post, 'mod_services_catalog');
    if (!is_wp_error($terms) && !empty($terms) && is_object($terms[0])) {
        $taxonomy_slug = get_term_parents_list($terms[0]->term_id, 'mod_services_catalog', array(
            'separator' => '/', 'format' => 'slug', 'link' => false, 'inclusive' => true
        ));
        $taxonomy_slug = trim($taxonomy_slug, '/');
    } else {
        $taxonomy_slug = 'categories';
    }
    return str_replace('catalog', 'catalog/' . $taxonomy_slug, $permalink);
}

/**
 * Создаём новые правила перезаписи +
 * - taxonomy_slug_rewrite()
 */
add_filter('generate_rewrite_rules', 'taxonomy_slug_rewrite');
function taxonomy_slug_rewrite($wp_rewrite)
{
    $rules = array();
    $taxonomies = get_terms(array(
        'taxonomy' => 'mod_services_catalog', 'hide_empty' => false
    ));
    foreach ($taxonomies as $taxonomy) {
        $taxonomy_slug = get_term_parents_list($taxonomy->term_id, 'mod_services_catalog', array(
            'separator' => '/', 'format' => 'slug', 'link' => false, 'inclusive' => true
        ));
        $rules['^catalog/' . $taxonomy_slug . '?$'] = 'index.php?' . $taxonomy->taxonomy . '=' . $taxonomy->slug;
    }
    $rules['^catalog/([^/]*)/?$'] = 'index.php?mod_services_catalog=$matches[1]';
    $rules['^catalog/(.+?)/page/?([0-9]{1,})/?$'] = 'index.php?mod_services_catalog=$matches[1]&paged=$matches[2]';
    $rules['^catalog/(.+?)/([^/]*)/?$'] = 'index.php?mod_services=$matches[2]';
    $wp_rewrite->rules = $rules + $wp_rewrite->rules;
}

/**
 * Обновляем правила перезаписи при создании/удалении/изменении таксономий
 * - hc_reset_rewrite_rules()
 */
add_action('created_mod_services_catalog', 'hc_reset_rewrite_rules');
add_action('delete_mod_services_catalog', 'hc_reset_rewrite_rules');
add_action('edited_mod_services_catalog', 'hc_reset_rewrite_rules');
add_action('save_mod_services_catalog', 'hc_reset_rewrite_rules');
function hc_reset_rewrite_rules()
{
    flush_rewrite_rules();
}

This code is the solution to the question: How to create a permalink structure for custom post types and taxonomies (nested terms)?