If the other party applies for patent protection, it is illegal. The patent number will be marked on the product. You can check it for the State Intellectual Property Office at /sipo2008/zljs/. You can use Patent Law 60 Article 9 Any of the following circumstances will not be regarded as infringement of patent rights: (2) The same product has been manufactured, the same method has been used before the patent application date, or the necessary preparations for manufacturing and use have been made, and manufacturing will only continue within the original scope , used; defense