iPhone randomly restarts

Hey guys! Lately my iPhone13 has been randomly restarting. When this happens, a black screen appears alongside with a spinning loading symbol (I’ve attached a similar photo of what this looks like). When the phone does restart, it doesn’t refresh any of my apps like a normal restart would. If I was watching a YouTube video or an Instagram video before the restart, I would still be able to go back into the app and watch view that same video. Also, the restart thing does not kick me out of FaceTime either.

if anyone could tell me what’s happening, or any solutions, that would be very helpful. Thanks heaps.