使用优惠券获取某个属性无效（已完成一些代码）

Question

I am trying to get it so the coupons do not work with anything with the attribute of extract-flavor = agave.

There are 2 Extract Flavors Coconut Oil & Agave - I want agave to be invalid with ALL coupons

I have tried the below code, it just makes all coupons invalid

add_filter( 'woocommerce_coupon_is_valid', 
   'check_if_coupons_are_valid', 10, 3 );
    function check_if_coupons_are_valid( $is_valid, $coupon, $discount ){
      // YOUR ATTRIBUTE SETTINGS BELOW:
     $taxonomy   = 'pa_extract-flavor';
     $term_slugs = 'agave';

     // Loop through cart items and check for backordered items
       foreach ( WC()->cart->get_cart() as $cart_item ) {
        foreach( $cart_item['variation'] as $attribute => $term_slug ) {
             if( $attribute === 'attribute_'.$taxonomy ) {
                $is_valid = false; // attribute found, coupons are not valid
                break; // Stop and exit from the loop
               }
          }
        }
         return $is_valid;
        }

I expect it to make all coupons being used on the extract flavors that is agave invalid, but it makes all coupons invalid on all products

thanks