@Nodsey: To close the app completely, you can tap the Home button in your Navigation Bar, followed by the Recents button, and swipe upwards on the Samsung Music preview window. If you would like your music to stop when you press the Home button, try heading to Settings > Apps > Samsung Music > Battery > Allow background activity, and toggle this option off. You could also try heading to Settings > Battery and device care > Battery > Background usage limits > Deep sleeping apps > Tap the '+' in the top right corner > Samsung Music > Add. Let me know if this helps.
@Nodsey: That's strange, as both these options should be available to you on Android 12. When you head to Settings > Battery and device care > Battery, the Background usage limits option should be visible below Power saving (below the usage graph). If you're having trouble find these features then you can head to the Settings menu (swipe up from your Home Screen > Settings (cog symbol)) and use the search function at the top of the screen to find them.
