Only 6% of China's coal are imported

https://www.worldometers.info/coal/china-coal/

In 2019, about 96.3 percent of China’s coal imports came from Australia (77 million metric tons), Indonesia (47.8  million metric tons), Mongolia (36.1 million tons), and Russia (29.2 million metric tons). Prior to 2017, North Korea was China’s fourth largest coal supplier, ahead of Indonesia and Mongolia. Due to the implementation of UN sanctions on North Korea, China has suspended all coal imports from the regime. As a result, China has shifted to rely more on Russia and Mongolia to fulfill its coal needs.

The recent power outage is self-inflicted.  It seems like the government learned a lesson.