Because China's patent law stipulates that inventions protected by patents should be "novel, creative and practical", among which "novelty" means that the same inventions have not been recorded in public publications before the date of patent application, are not known to the public in other ways, and there is no conflicting application. Therefore, patents that have been applied for abroad generally cannot be applied for in China, because there is no novelty, otherwise it is very simple to retrieve some foreign patents and apply for patents in China. However, in practice, because the invention patent has been substantially examined, the utility model patent and the design patent can be authorized without international retrieval.
Of course, if you apply for a domestic patent, you may still be authorized after modifying the technical scheme.