When an item is on sale, I believe it should show as on sale clearly in the item list, not just in the cart, ideally with a strikethrough of original price and sale price right next to it (in larger font - see next). Showing the lowest possible price in the item list leads to more sales. Check out "Locating Discounts Far Away from the Product Price" item #2 here (example given is actually case where discount only shows in cart): https://baymard.com/blog/product-page-price-discounts.

4 here discusses the psychology behind a font change driving ecommerce sales, specifically "Your sale price should be in a smaller font, whereas your discount should be advertised using a larger one": https://www.namogoo.com/blog/consumer-behavior-psychology/psychology-of-discounts/