Find an agency registered in China National Intellectual Property Administration to apply for a patent, which has a high reputation and credibility. First, the state is bound by laws and regulations such as patent agency regulations. If there is a leak, you can find the local intellectual property department to deal with it. Second, these formal institutions should also cultivate their own brands and word of mouth. If there are leaks and disputes, it is impossible to gain a foothold in this industry.
So just find a professional and formal company that can meet your needs.