Are the profits offered by Islamic banks permissible, taking into consideration that they may be determined by the state's central bank?

Islamic banks operate on the Mudarabah (profit-sharing) system, where the profit ratio is attributed to the profits themselves, not to the capital. If the percentage is taken from the capital as a guarantee, the transaction becomes invalid because it falls under the category of guaranteeing a specific sum of money. However, if it is an expected percentage based on previous studies, without any commitment from the bank, this does not affect the validity of the transaction. As for Murabahah (cost-plus financing) sales, determining the profit margin is permissible, whether by the bank or at the request of the Central Bank.