https://penusbmic.itch.io/sci-fi-character-pack-8 's price is 0. With an optional bonus file, if you pay $ 1.50 or more. The project is on discount at 50% which you can not see on the page itself, but in the catalogue. https://itch.io/game-assets/on-sale/tag-science-fiction/tag-side-scroller/tag-to... right next to the name it says -50% but without a minimum price to calculate the new price.
https://penusbmic.itch.io/sci-fi-dark-edition-character-add-on 's price is $ 4.99 without discount and currently $ 2.49, because the discount is calculated on page to show the new minimum price.
Both packs are on discount and in a bundle. You do not see the discount on page for the 0 minimum price project, because it does not have a minimum price where the discount could be applied.
I do not know what it means when a 0 price project is on discount and how discounts are applied to these individually priced files: https://itch.io/docs/creators/pricing#purchase-tiers-through-individually-priced...
For that matter, I also do not know how bundle prices are calculated, if the items in the bundle have such files. Or how a bundle discount would apply.