Movies on iPhone do not auto stop playing

Alright so here is the context:

I go to sleep considerably late than my spouse, but I like to listen to something when I go to sleep. So I'll usually pop in my AirPods (or just one) and start playing a movie on my iPhone X.

I put my iPhone X on its wireless charger and I fall asleep with the movie playing. But here's the rub: when I wake up multiple hours later the movie is still playing, almost as if it is looping.

This is completely new, because I used to be able to fall asleep and the movie would stop playing after it ended.

Can anyone tell me why this might be happening?