Their cellphones are monitored and they “call home” regularly. If they have family in China then they are sending back every scrap of information they can find.
My openly vocal hate for the CCP, military past, and long history in China makes me more likely for monitoring by the ChiComs than most Chinese immigrants.
Most Chinese immigrants here are very apolitical, but those who still defend the CCP are a definite threat. There should not be ANY PhD or STEM research going on in any US University or corporations by any Chinese nationals at this point.