FaceTime Automatically hanging up overnight?

Why can’t I stay in a FaceTime call overnight with my iPhone 11? Each night, I FaceTime my partner and we will fall asleep on the line. When I wake up and check my phone, I can see the call only lasted for an hour and a few minutes. Neither of us hang it up “accidentally” and no, airplane mode is not on. Neither of us have anything in screen time enabled either. I contacted my carrier and there’s nothing they can do on their end.