/**
 * Filter to show brand value in snippet preview.
 */
add_filter( 'rank_math/vars/replacements', function( $vars ) {
    global $product;

    if ( ! $product ) {
        return $vars;
    }

    if ( isset( $vars['wc_brand'] ) ) {
        $brand = $product->get_attribute('pa_brand');

        // Use this code to get 1st element from brand attribute if multiple brands are assigned to a Product.
        $brands = explode( ',', $brand );
        if ( ! empty( $brands ) ) {
            $brand = $brands[0];
        }

        $vars['wc_brand']['example'] = $brand;
    }

  return $vars;
});

/**
 * Filter to replace wc_brand with custom value.
 */
add_filter( 'rank_math/replacements', function( $replacements ) {
    if ( is_singular( 'product' ) && isset( $replacements['%wc_brand%'] ) ) {
        $product = wc_get_product();

        $brand = $product->get_attribute('pa_brand');
        // Use this code to get 1st element from brand attribute if multiple brands are assigned to a Product.
        $brands = explode( ',', $brand );
        if ( ! empty( $brands ) ) {
            $brand = $brands[0];
        }

        $replacements['%wc_brand%'] = $brand; // Pass $brand to set meta value for brand.
    }
    return $replacements;
});