How can I tell if my child's flat feet are causing them pain or discomfort?

Hi there, as a parent, I am concerned about my child's flat feet and how it might affect their daily activities. I am not sure if their flat feet are causing them pain or discomfort as they never say as much. I want to make sure they receive appropriate care and treatment if necessary. Can anyone provide some advice about how to tell if my child's flat feet are causing them problems? Any suggestions would be greatly appreciated.