Currently "Buy X and Get Y" discount is only related to the whole order and not at the order item level.
I needed order item level discounts. e.g. buy 10 or more of the same product and get 10% off that order item.
The new promotion will only discount at the order item level for order items with a quantity of 10 or more.
Example - Buy 10 or more and get a 10% discount.
Order Item 1 - Quantity of 5 - No Discount
Order Item 2 - Quantity of 11 - 10% off discount
Order item 3 - Quantity of 10 - 10% off discount
Order Item 4 - Quantity of 1 - No Discount
I have created a patch for this type of discount. The discount is labeled: "Buy X per order item get a percentage off." The new promotion only allows only for a percentage off discount and does not include a fixed amount discount.
Drupal Commerce Issue Queue: https://www.drupal.org/project/commerce/issues/3066724