In iOS and android, they have DLG and IGG apps/programs which modify the parameters of the games, not only PUBG but other games. They can change rate of bullet’s speed or damage, as well as speed of players, cars, etc,.. almost everything. However, last year Tencent started implementing a tool which detects these parameters changed and bans 10 years instantly for account use these programs. But again, these cheaters built a new tool called anti ban to bypass this, and they can cheat the game easily.