Actually, it all boils down to the issue of intelligence leakage within the Dongye State Security Bureau system.
Because the people in the Dongye State Security Bureau were all promoted by Dai Yukang, it's like a sieve.
It's impossible to hide intelligence from Dai Yukang in Dongye State.
And now Dai Yukang is a direct lineage of Huang Shangzong. Knowing Xue'er's intelligence, he'll definitely report it to Huang Shangzong immediately.
This is why Huang Shangzong led his troops to Dongye State (as Dai Yukang thinks).
And after this incident passed, Rain Butterfly obviously discovered the problems within the Dongye State Security Bureau.
So, before Qiu Tu left Dongye State, she began cleaning up the entire Security Bureau system.
The infighting within intelligence systems can be resolved if both parties are courteous to each other.
Once one side tears the facade, the methods become ruthlessly cruel, and the punishment is exceptionally harsh.
