How much RAM does your phone have (I think you all have 8GB)? And then before you run PUBG game, how much is it currently in use? I tend to keep mine below 4GB, so that is a little over 50% free for the game you play.
This is why ROG is allow more easier in this case, because you can deny those annoying auto start up apps which you don't need that's taking up valuable memory.
PUBG is resource intensive, so it's better to have not alot running.
Running out of memory can cause your phone to restart.