As I understand it, China's GFW is intentionally leaky, balancing as much control as they can get away with but not enough to forment open revolt. As with a lot of things, the best control is not total control.

Also not revealing their capabilities. During normal times, some VPNs work. Whenever there is a protest in Beijing, suddenly, none of them work any more.

except this implies total control, and a willingness to use that control to gaslight your citizens into believing they have some control