Are the profits obtained from investing the money deposited in savings accounts, of which the bank allocates 30% to cover its administrative expenses, permissible (halal)?

If the bank adheres to the Sharia guidelines for a Mudarabah contract, then the transaction and its profits are permissible (halal). However, if it does not adhere to these guidelines, such as guaranteeing the principal amount and the investor not bearing any loss, then the transaction is forbidden (haram) and the profits are usury (riba).