What is the ruling on taking a commission from a client for selling airline tickets without their knowledge, given that the company gives the employee a percentage of the commission profits?

There is no objection to the booking office taking a commission on airline tickets, and it is not required to inform customers of this; because it is known that these offices take a commission for booking tickets, as they are established for this work and are not voluntarily doing it. And what the office gives you as a commission is permissible.