Are the administrative fees and charges of Islamic banks, and the 7% or more or less that they take to sustain their capital, permissible?

Banks are permitted to charge fees and administrative expenses for their services. For credit services, it is stipulated that these expenses must be a fixed amount, proportionate to the effort, not excessive, and not a percentage; otherwise, it would be a ruse to legitimize usury. The essence of contracts lies in their realities, not merely in their wording, and a ruse does not make the unlawful lawful; rather, it increases its sinfulness. Allah has punished those who sought to make unlawful acts lawful through stratagems, and the Prophet, peace and blessings be upon him, forbade committing what the Jews committed by legitimizing Allah's prohibitions through the slightest stratagems.