All products included in the promotion are clearly marked with this sentence in description:
🔥 Buy 1 = 1 at 50% / Buy 2 = 1 free / Buy 3 = 2 free 🔥
Buy 1, get the 2nd at 50%
*You must add a minimum of 2 products included in the promotion to your cart for the promotion to apply.
Buy 2, get 1 free
*You must add a minimum of 3 products included in the promotion to your cart for the promotion to apply.
Buy 3, get 2 free
*You must add a minimum of 5 products included in the promotion to your cart for the promotion to apply.
As well as a banner on the product image, top left:
If you don't see this sentence and the banner, it means the product is not included in the main promotion.