Is it permissible to save for children in Bank Al-Zaytouna under the Murabaha system, where an unknown amount of profit is added every three months until the child reaches the age of eighteen?

If the bank invests money in permissible projects, it is permissible to place money in an investment or savings account, provided that the principal is not guaranteed and a known percentage of the profit is agreed upon for the investor. Murabaha is the sale of a commodity at its cost price with a known profit. It is permissible for the bank to invest funds in purchasing commodities and selling them through Murabaha. However, reverse Murabaha (reverse Tawarruq) is prohibited. It involves a client depositing money in the bank, then authorizing the bank to purchase a commodity for the client and sell it to itself through Murabaha to obtain a profit. Decisions prohibiting it have been issued by Islamic Fiqh Councils. The contract should be presented to scholars to verify whether it is permissible or prohibited.