Over heating

My new iPhone14 is getting heat and shut down after using FaceTime for 10mins. I have visited apple care twice they show all reports and know my phone shut down due to overheating. But they told me it’s normal. They are asking me to expect less from phone means they told me I should do video call less then 5mins. I can’t understand why do they answer like it. Should we do only five minutes call after buying latest product from apple. Really disappointed. What should I do now I don’t know. Any help will appreciate. Thanks