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Try to play it with 50% or less brightness. I do some research that playing PUBG with brightness set on 30% or less with set on 50% or more is totally different both heat and battery drain. Try this and see if it could fix your problems. Because this method work for me. ?
I am facing the exact same issue. The game lags horribly (it has never lagged before for me) and the phone heats up in no time. The latest software does not allow me to revert back to the previous version also (10.2.2.0 or lower). If there is no other option the only alternative perhaps is to unlock the bootloader and flash the ROM, but that's quite a tedious process and will erase all the data on the phone.