And just to remind people. "Rare Earth" materials aren't actually rare. They're common. However, they are distributed in very very low concentrations, so you have to go throw mountains worth of material to extract measurable amounts of Rare Earth materials. This is typically energy intensive and ecologically destructive, which in most of the work equals "expensive" which is why the nations of the world have been happy to shut down their own Rare Earth extractions facilities any paying China to destroy its ecology instead.
China is free to set up its restrictions on exports. Other nations are free to restart their own extraction operations (with the costs that come with it).
This effectively makes all minerals the state's property and prevents commerce with other nations who specialize in heavy machinery or electronics including: USA, UK, EU, SK, and Japan.
Previously, Beijing already started enforcing a ban on exports of REE and related technology exports.
The new regulations include a strict database on REEs outlining when and where they were extracted all the way to where they're exported. The laws stipulate that "no organization or person may encroach on or destroy rare-earth resources."
What is best for China is peaceful coexistence and small concessions to incentivize trade and development of the world.
What China is doing is maliciously taking everything they can get their hands on until every bridge is burned, and by the looks of it they're ramping up military production to cross the river and keep taking.
Exactly the sort of shortsighted belligerent actions you would expect from a dictatorship.