Please check the following steps:
1. Install ASUS Log Tool .
2.Use the default log settings then start to reproduce this error.
3. Share the pics of battery percentage before playing "PUBG".
4. Begin to play PUBG and charging at the same time, when you find the battery decreased (the 18W adapter still connect on phone), please generate the log as below and record the times, such as 2019/10/29, 15:45 got the error! (removed image)
5. Share the all files from "save log" as below thruogh google drive or any cloud storage
6. Share the pics of battery usage as below, from: settings>battery>click the battery icon and you'll get battery usage. (removed image)
steps provided by Asus
try it guys!