I'm having issues with my S10+ losing all of my recently paired devices over Bluetooth. This has happened TWICE now in probably two months with one of those times being yesterday. I lose every bit of it and have to reconnect it all. The worst and most annoying thing is it loses my Samsung Watch 4. The wearable app loses any existence of my watch ever being connected and I had to reset my watch the first time it happened. I am really wanting to find a solution so that I don't have to reset my watch a second time, can anyone help? Thanks!
when it happens again, report to samsung using samsung members app > get help > error report
Also, try using Nice Catch to see if detects what is changing the settings (in your case, deleting the connected devices)