The only issue right now about China and magnets is that China has a world dominating position in possessing and processing the rare earth minerals essential for producing the powerful magnets used in electronic and military applications, and is willing to use that advantage.
Trump and his blackmailing beautiful tariffs is what caused China to push back with export restrictions. But as other countries develop their own rare earth minerals, China's dominance will fall.
I cannot fault their use of a currently effective trade weapon to counter Trump's attempts to damage their economy. Or to put it in Trump's words - China has all the cards.
I just wish other countries had the ability to fight back too. Consumers around the world are paying for Trump's bloody tariffs.