During work, use the company's resources (manpower, financial resources, material resources, etc.). ) designing and developing products for the company, applying for a patent is called "service invention". The intellectual property of "service invention" belongs to the company, and individuals are only "inventors" and do not own intellectual property rights.
If you have left the original company for more than one year and have not violated the confidentiality agreement and employment prohibition agreement signed with the original company, then the intellectual property rights of your R&D and design are of course your own.
If the "service invention" clearly stipulates the ownership of intellectual property rights, the ownership shall follow its agreement.
Signing an agreement with the company in advance to clearly stipulate the ownership of intellectual property rights is the best way to protect your rights and interests.
What the designer did in the title is illegal.