Hi, I am using a Samsung s23 and with the one UI 6 and now even with the one UI 7 I have the same issue: the player disappears after I pause a track.
If I have a track playing and I click pause with my headphones, then I click it again to restart playing and it doesn’t work, I unlock the phone to find out that the player has disappeared from the notification bar. So I have to unlock the phone and open the app again in order to restart playing a track. Every time.