Missing Fields Google Search Console

Hi,

I have the following missing rich snippets:

Missing field ‘brand’
No global identifier provided (e.g. gtin, mpn, isbn)

I added below code in my function.php but that did not make any difference.

// Add Brand for Products.
add_filter( ‘rank_math/snippet/rich_snippet_product_entity’, function( $entity ) {
$entity[‘brand’] = ‘Shopping Brand’;
return $entity;
});