What is the ruling on a website for selling goods deducting a specific amount from the seller, then taking an additional percentage from the price of the item if it is sold, and sufficing with the initial amount if it is not sold?

It is permissible to display goods on the aforementioned website for a known fee, provided that the advertisement is free of forbidden elements such as music and images of women. However, if the additional percentage is merely for facilitating the sale, this leads to an unknown fee. But if it is in exchange for additional work from the website, such as e-marketing, then there is no harm in taking an additional amount, and the permissibility of it being a percentage of the item's price is a matter of scholarly disagreement.