Seeing as China seems to just kill US spies I don't think there's much of a gentlemen's agreement. They just take advantage of the 'the West's' soft approach to national security. Same as they use gray war tactics in the South China Sea knowing there's nothing we can do about it seeming like bad guys.

The CIA falsely believed it was 'invincible' in China — here's how its spies were reportedly discovered and killed in one of the biggest blows to the agency
https://www.businessinsider.com/how-...es-leak-2018-8

Though it's from the last Trump presidency I think it's something the CIA has likely not been able to recover from. The Chinese language/ character system are sort of a natural barrier to more US recruitment and make it hard for casual intercepts as well as that there's not that many westerners in the PRC and those that are, are under close scrutiny by a very 1984-esque state security infrastructure.