iPhone automatically answering calls when I’m on the other line

My iPhone is automatically answering phone calls when I’m already on the phone. If I am not on the phone, it rings like normal and allows me to answer the phone myself. But if I am on a FaceTime call, or a regular phone call and another call comes in, it will automatically switch over to the new call. This is not an auto answer issue. I have already checked my accessibility settings and auto answer is not turned on. This is a brand new iPhone 13 and the updates are up-to-date. This problem never happened on my old phone, just this new one. What do I do?