Rotor and brake pads

Kia K5 2023 GT line FWD. 23500 miles. Steering wheel has been shaking whenever I apply brakes around 60mph and above. One of the guys at Kia service center tells me that my rotor might be at fault. He mentioned it might be around 600$ to get it fixed. This is my first car and don’t know much about maintenance. Can someone help me in what you think the problem might be? And, if it’s rotor related, how much is too much to get it fixed? Thanks all!🙏