The Chinese aren't buying up farmland outright, they are investing in US farmland production. They invest to earn money, not food. The US prohibits Chinese corporations that are tied to the Chinese military from investing in any US business.
The 2 problems there are that the US agencies that are supposed to vet Chinese investors don't always do a thorough job, and Chinese investors are very good at hiding ties to the PLA. Plus, we all know that directors of US agencies are corruptible and Chinese businessmen can afford to grease palms generously.
That said, like I posted way earlier, I doubt the CCP (as we know it) will survive another 5 years. Maybe 10 at the most.
There's internal conflict between the "prince-lings" and Xi, extreme conflict between the 2 political factions of the top CCP officials, dissatisfaction between the PLA generals and Xi, and the Chinese people themselves are extremely dissatisfied with the CCP and Xi and the prince-lings, and they're getting more and more bold about it.