BEIJING :China, the world's top processor of rare earths, banned the export of technology to extract and separate the critical materials on Thursday, the country's latest step to protect its dominance over several strategic metals.Rare earths are a group of 17 metals used to make magnets that turn power into
China doesn't need to produce the fast chips because their comparative advantage is in quantity manufacturing.
Sure thing, until you realize that China isn't that big at all as the 5th largest producer of semiconductors behind Taiwan, Korea, Japan and the USA:
https://worldpopulationreview.com/country-rankings/semiconductor-manufacturing-by-country
China is listed as the largest and 5th largest in your source