When importing from Printify service to Woocommerse, the variations in attributes do not match color, size and price. I transferred attributes to global and variations are posted in a scatter. Here is the code that is available.

The code already handles colors and sizes correctly, but does not update prices for variations. To add support for Printify prices

    add_action('rest_after_insert_product', function($product) {
    $product_id = $product->get_id();
    error_log("Processing product: $product_id");
    
    convert_custom_to_global_attributes($product_id);
    update_variation_prices($product_id);
}, 10, 1);

add_action('shutdown', function() {
    global $wpdb;
    $products = $wpdb->get_col("SELECT ID FROM {$wpdb->posts} WHERE post_type = 'product' AND post_status = 'publish'");
    foreach ($products as $product_id) {
        convert_custom_to_global_attributes($product_id);
    }
});

add_action('woocommerce_before_single_product', function() {
    $product = wc_get_product(get_the_ID());
    $attributes = $product->get_attributes();
    error_log("Product attributes: " . print_r($attributes, true));
});

function convert_custom_to_global_attributes($product_id) {
    $product = wc_get_product($product_id);

    if (!$product) {
        error_log("Product not found: $product_id");
        return;
    }

    $attributes = $product->get_attributes();
    $updated_attributes = []; // To store only global attributes
    $attribute_mapping = [
    'custom_sizes' => 'pa_sizes',
    'custom_colors' => 'pa_colors',
];
    foreach ($attributes as $key => $attr) {
        if (!$attr->is_taxonomy()) { // Check if it's a custom attribute
            $name = $attr->get_name();
            $taxonomy = 'pa_' . sanitize_title($name);

            // Create the global attribute if it doesn't exist
            if (!taxonomy_exists($taxonomy)) {
                $result = wc_create_attribute([
                    'name'         => $name,
                    'slug'         => sanitize_title($name),
                    'type'         => 'select',
                    'order_by'     => 'menu_order',
                    'has_archives' => false,
                ]);

                if (is_wp_error($result)) {
                    error_log("Failed to create global attribute $name: " . $result->get_error_message());
                    continue;
                }

                register_taxonomy($taxonomy, 'product', [
                    'hierarchical' => true,
                    'show_ui'      => false,
                    'query_var'    => true,
                    'rewrite'      => false,
                ]);
            }

            // Convert terms to global taxonomy terms
            $options = $attr->get_options();
            foreach ($options as $option) {
    if (!term_exists($option, $taxonomy)) {
        $term_result = wp_insert_term($option, $taxonomy);

        if (is_wp_error($term_result)) {
            error_log("Failed to create term '$option' in taxonomy '$taxonomy': " . $term_result->get_error_message());
        } else {
            error_log("Created term '$option' in taxonomy '$taxonomy'.");
            error_log("Variation $variation_id original attributes: " . print_r($variation_attributes, true));
            error_log("Updated attributes for variation $variation_id: " . print_r($updated_variation_attributes, true));
        }
    }
}

            // Prepare the global attribute
            $global_attribute = new WC_Product_Attribute();
            $global_attribute->set_id(wc_attribute_taxonomy_id_by_name($name));
            $global_attribute->set_name($taxonomy);
            $global_attribute->set_options($options);
            $global_attribute->set_visible($attr->get_visible());
            $global_attribute->set_variation($attr->get_variation());

            $updated_attributes[$taxonomy] = $global_attribute; // Add to updated attributes
            $attribute_mapping[$name] = $taxonomy; // Map old attribute name to global taxonomy
            $attribute_mapping = [
             'custom_sizes' => 'pa_sizes',
             'custom_colors' => 'pa_colors',
          ];
        } else {
            // Keep existing global attributes
            
            $updated_attributes[$key] = $attr;
        }
    }

    // Update the product with only the global attributes
    $product->set_attributes($updated_attributes);
    $product->save();
    
    // Update variations to use global attributes
    update_variation_attributes($product_id, $attribute_mapping);
}

function update_variation_attributes($product_id, $attribute_mapping) {
    $product = wc_get_product($product_id);

    if (!$product || !$product->is_type('variable')) {
        error_log("Product $product_id is not variable or not found.");
        return;
    }

    $variations = $product->get_children();
    $used_sizes = [];
    $used_colors = [];

    foreach ($variations as $variation_index => $variation_id) {
        $variation = wc_get_product($variation_id);

        if (!$variation) {
            error_log("Variation $variation_id not found for product $product_id.");
            continue;
        }

        $updated_attributes = [];
        $missing_attributes = [];
        $current_attributes = $variation->get_attributes();

        foreach ($attribute_mapping as $custom_name => $global_taxonomy) {
            $custom_value = $variation->get_attribute($custom_name);

            if ($custom_value) {
                $term = get_term_by('name', $custom_value, $global_taxonomy);
                if ($term) {
                    // Проверяем, нет ли уже атрибута в текущих значениях
                    if (!isset($current_attributes['attribute_' . $global_taxonomy]) || $current_attributes['attribute_' . $global_taxonomy] !== $term->slug) {
                        $updated_attributes['attribute_' . $global_taxonomy] = $term->slug;
                        error_log("Variation $variation_id: Mapped '$custom_name' to global term '{$term->slug}' in taxonomy '$global_taxonomy'.");
                    }

                    // Добавляем в списки использованных атрибутов
                    if ($global_taxonomy === 'pa_sizes') {
                        $used_sizes[] = $term->slug;
                    }
                    if ($global_taxonomy === 'pa_colors') {
                        $used_colors[] = $term->slug;
                    }
                } else {
                    $missing_attributes[] = $global_taxonomy;
                    error_log("Variation $variation_id: Term '$custom_value' not found in taxonomy '$global_taxonomy'.");
                }
            } else {
                // Распределение терминов, если значение отсутствует
                $attribute_terms = get_terms([
                    'taxonomy' => $global_taxonomy,
                    'hide_empty' => false,
                ]);

                if (!empty($attribute_terms)) {
                    $term_slug = $attribute_terms[$variation_index % count($attribute_terms)]->slug;

                    // Проверяем, чтобы термин не дублировался
                    if (
                        ($global_taxonomy === 'pa_sizes' && !in_array($term_slug, $used_sizes)) ||
                        ($global_taxonomy === 'pa_colors' && !in_array($term_slug, $used_colors))
                    ) {
                        $updated_attributes['attribute_' . $global_taxonomy] = $term_slug;
                        error_log("Variation $variation_id: Assigned term '{$term_slug}' for '$global_taxonomy'.");
                    }
                } else {
                    $missing_attributes[] = $global_taxonomy;
                    error_log("Variation $variation_id: No terms available for taxonomy '$global_taxonomy'.");
                }
            }
        }

        if (!empty($updated_attributes)) {
            // Устанавливаем новые атрибуты и сохраняем вариацию
            $variation->set_attributes(array_merge($current_attributes, $updated_attributes));
            $variation->save();
            
        } else {
            error_log("No attributes updated for variation $variation_id of product $product_id. Missing attributes: " . implode(', ', $missing_attributes));
        }
    }

    // Синхронизация продукта
    WC_Product_Variable::sync($product_id);
    wc_delete_product_transients($product_id);
}