Talking about cleaners isn't forbidden, it's just that it can't be discussed here.
Gao Yang was well aware that the cleaners had been acting quite unusually lately. As a secret organization, their name gave it away—cleaners, as the name suggests, are meant to clean up traces. When Gao Yang first got in touch with them, the only service they provided was cleaning up the aftermath.
In simple terms, cleaners are those who sweep the battlefield and erase evidence. But after Gao Yang's level increased, and after encountering Murphy, cleaners were no longer just about cleaning services.
When Tomler was eliminated, the cleaners didn't directly send people to participate in the operation, but they were prepared in advance, and it was Murphy who recommended Number Thirteen to Gao Yang.
