Audio keeps playing in the background after locking or putting the screen to sleep
On Android mobile devices, iPhone, and iPad, if you lock or put the screen to sleep (for example, by pressing the side button) while a title is playing, the Netflix app will continue to play the title's audio in the background.
Note: Background audio playback is not available on an ad-supported experience.
To prevent audio from playing in the background, pause the title before locking your device or putting the screen to sleep.
To stop audio that's already playing in the background, you can:
Unlock your device, open the Netflix app, and pause the title.
Tap the screen or press the wake/sleep button, then press the Pause button on the player.