Somethings wrong with the sound

I experience the same thing sometimes when playing video. It's not limited to Disney+. I find that if I play a video clip in the Photos app, and go back, the sound continues to play.

The solution is to either go back in the video and stop it manually. Or close the app completely. Open the App Swither and swipe the app - in your case Disney+ up and away.

I'm on iOS 26.0.1 - it's possibly a bug that can be fixed in a later update. Never thought I experienced that when I was on iOS 18.

It is not a bug

It is how Apple Music or Spotify work. If you pay youtube a monthly fee they also allow you to play audio with the phone locked to play music..