"If it's not man-made, then it means that he knows this hotel quite well and has been preparing for this opportunity."
Yun Xiangxiang guessed that this person probably knew that the hotel often had power outages. He was either waiting for an opportunity or using this characteristic.
Then he had to frame Yun Xiangxiang first before poisoning Gao Qiu. After all, mercury poisoning happened very quickly. It only took five to six minutes.
If he had poisoned them first, there was no way he would have waited for the power outage. Even if he had controlled the power outage, the possibility of an accident was too high. Therefore, he knew that Yun Xiangxiang and the others had not been in the room for a long time, so he would frame Gao Qiu first.
After the frame was successfully planted, he would poison Gao Qiu.