Is there a risk that major inventions will be leaked during the patent application process?

The key lies in economic value. The greater the value, the greater the risk. Someone told you that the agency process was safe, and he didn't lie to you. That's because his subconscious thought your invention was of little value. The value is not high, and there is really no risk.

There is no risk in applying for it yourself. It is risky to ask an agent or an agent. You don't want to give it to him unless he doesn't like your invention. If you like, in theory, they can go directly to China and hand over the application materials to the relevant personnel. The application date is theirs before you. Although you signed a confidentiality agreement, it is difficult to find evidence of leakage and theft. Objectively speaking, others can invent at the same time as you! Even if you have a little evidence, it is not so easy to go to court. This may be a loophole in China's patent application system!