Are the profits earned from financial participation in an Algerian institution specializing in building and selling housing units, where the shareholders' profit is predetermined, permissible or forbidden?

This issue is closer to Mudarabah (profit-sharing partnership), which is permissible if it fulfills its conditions. The most important of these conditions are: that the capital is not guaranteed, and that the percentage of profit is from the actual profit. However, if the company pre-determines the profit by a fixed amount, then whether a profit is made or not, this transaction is forbidden and falls under the category of a loan with interest, because it involves returning to the contributor what they paid along with an increase, and this is precisely usury (riba).