China invention patent application and approval procedure is basically the process of disclosure and authorization after inventor's application and patent examination. The inventor's situation before the application is only known to the applicant himself. If, as you said, his own innovative method, the company applied for a patent, but there is no his own signature, this is mainly because the application process of the invention patent has not been made public so far. Inventors don't know that companies or others have applied for their own patents, and there is no place to prove their inventions through litigation. More importantly, many units rudely take employees' achievements as their own.
I also know that you don't want anything substantial. I just feel that this achievement is what you paid, and it is indeed your own wisdom, which is not reflected and somewhat lost. How original achievements respect facts and make real inventors worthy of the name is an important force in the development of science and technology.