I disconnected in the middle of a game- my app turned off- as a result of my smartphone os turning on Focus Mode. I tried reconnecting and opened the app within seconds. But I couldn't get back into the game or even start a new one. The game didn't even show in my history. This suggests that it was still live and I couldn't get back in until the disconnect timer ran out.
There should be an option to get back in live games if the timer hasn't run out, even and especially if the app was closed.