Remove attributes not used for variations when saving product

Question

I am importing products through CSV from a POS software and it is creating a lot of unnecessary attributes which are not used, and I would like to delete them automatically if they are not used for variations.

I found this code from another question which works great to process all my products.

But I would like to do it automatically for new products that will be imported in the future.

So I've wrote this code to delete the attributes not used for variations when a product is saved:

$postType = "product";

add_action("save_post_" . $postType, function ($post_ID, \WP_Post $post, $update) {

        // Get the Variable product object (parent)
        $product = wc_get_product($post_ID);
    
        if ($product->is_type( 'variable' )){
        
            $va = $product->get_variation_attributes();
            $vas = [];
            foreach ( $product->get_attributes() as $attribute ) {
              if ( isset( $attribute['is_taxonomy'] ) && $attribute['is_taxonomy'] ) {
                $terms = wp_get_post_terms( $product->id, $attribute['name'] ) ;
                foreach ( $terms as $term ) {
                  if ( in_array( $term->slug, $va[ $attribute['name'] ] ) ) {
                    if ( ! isset( $vas[$attribute['name']] ) ) {
                      $vas[$attribute['name']] = [];
                    }
                    $vas[$attribute['name']][] = $term->term_id;
                  }
                }
              }
            }
            foreach ($vas as $tax => $vals) {
              wp_set_post_terms(  $product->id, $vals, $tax  );
            }
            
        }


}, 10, 3);

I can see in the log that the code is executed (including the wp_set_post_terms function call), but the product attributes are not changed. Can you please help?