Why does my iPhone keep randomly switching off?

I have this problem with my iPhone X where throughout the day, even at say 53% battery left, it randomly switches itself off. I wouldn’t mind so much if I could just switch it back on but the issue is that I can’t switch it back on by it’s own power, it has to be plugged into a power source, whether it be a PC or by a plug socket. Any ideas what might be causing this issue? I had thought of possible a faulty battery connector but if I switch it off normally and then switch it on normally it’s fine. Thanks.