I see it regularly - Chinese academics or research folks, who immigrated to the USA as adults, will often (not always though) have private companies and contacts back in China and will attempt to commercialize information and technology they have attained while working in the USA
This “industrial espionage” or technology leakage is the most common.
And yes, if it’s a very important technology targeted by the CCP, it will be outright government agents looking for this technology. This is less common, but still common enough - although the FBI has been chasing this for the last 15 years.
Started with Nixon and Slick Willie just open the barn door.