Fix Rankmath pro - product category schema

functions.php

<?php

add_filter('rank_math/json_ld', 'codetot_product_rich_snippet_schema', 100);

/**
 * Fix RankMath missing `AggregateRating` on product category schema
 *
 * @author codetot
 */
function codetot_product_rich_snippet_schema( $data ) {
    if ( !is_tax( 'product_cat' ) ) {
        return $data;
    }

    if ( isset( $data['ProductsPage']) ) {
        $product_schemas = array_map(function($product) {
            if ( empty($product['aggregateRating'] ) ) {
                $aggregateRating = [
                    '@type' => 'AggregateRating',
                    'ratingValue' => 5,
                    'ratingCount' => 1
                ];

                $product['aggregateRating'] = $aggregateRating;
            }

            return $product;
        }, $data['ProductsPage']['@graph'] );

        $data['ProductsPage']['@graph'] = $product_schemas;
    }

    return $data;
}