What is the ruling on working for a website that deducts a 20% tax and a percentage ranging between 30% and 12% of the profits?

It is permissible for the website to charge a fee for publishing designs, provided that the designs are permissible, and that the fee is known and agreed upon at the time of the contract. There is no objection to the fee being a known percentage of the price or profit, which is the view of the Hanbalis. If the percentage decreases according to a known and regulated formula, such as taking 20% on the first sale and then decreasing by 1% on each subsequent sale, there is no objection to that.