Upsells show only products shoppers can buy
Product upsells now skip products that are out of stock. Before, an out-of-stock product could take an upsell slot and show a button that did not work. Now every slot goes to a product the shopper can add to the cart: in the cart, in the empty cart and in the side upsells. This works for your upsell rules and for AI recommendations. A product that has at least one variant in stock still shows. You do not need to change any settings.