nefited most from china imposing an import quota on earth rare materials? Did it give the Chinese domestic manufacturers a significant cost advantage?...

Which groups benefited most from china imposing an import quota on earth rare materials? Did it give the Chinese domestic manufacturers a significant cost advantage? Did it result in dramatically increased quality and environmental standards?

The restrictions imposed by China on rare earth metals has resulted in some companies (e.g., Toyota, Renault, Tesla) starting to look for alternatives. They plan to use parts that do not include rare earth metals. Is this a good solution?