Clock app alarms are stopping recordings
Only if you set it up to do so.

The TIMER (not the Alarms) in the built-in Clock app on your iPhone and has a feature called Stop Playing, which will automatically turn off any music, movie, TV show, or video clip that is currently playing. It's perfect for setting your entertainment to turn off at a specific time.

Launch the Clock app on your iPhone. You can also access it from Control Center.


  Tap Timer in the bottom right corner of the screen.
  
  Select a length of time.
  
  Tap When Timer Ends.
  
  Scroll to the bottom and tap Stop Playing.
  
  Tap Set in the upper right corner of the screen.




You can set it back to "normal" not intrusive just a beep sound.

Or you can go completely silent with this app

https://itunes.apple.com/us/app/silent-alarm-free/id541446930?mt=8
OR you can se it to Vibrate only

https://www.live2tech.com/set-iphone-alarm-vibrate/

The choice is yours, but do not confuse the Alarms with Timer.