Help Bluetooth drops out shortly after pausing Bluetooth audio

If I'm listening to Spotify or Pocket Casts (or any other audio) on Bluetooth headphones, then pause the sound (from the headphones or the device), usually, within a couple of minutes, if I don't re-start the music, the bluetooth gets disabled.

When it happens, it seems the 2.x GHz system restarts - Wifi and Bluetooth disappear from the status bar, then a few seconds, WiFi comes back but I manually have to enable Bluetooth.

I've tested this on 2 phones Oukitel K6000 Pro phones, with 2 brands of bluetooth headphones (PSYC and Damson Headbones).

Anyone any ideas?