Audio stopping on iPad mini 6 or display turning of?

Audio I’m listening to stops, I open my eyes since. I fell asleep, display is off…Apple mini 6 display has turned off , I have to enter code for display to turn on, then the audio has just stopped and if I activate it, continues where it had stopped. Is it a setting I set wrong?

as I recall now, it also happened in same podcast I was listening to on my Android phone.

very uncomfortable situation !