Pretty much any new product gets a Chinese copy within a year. How are you so confident JLC is not the source of atleast some of these. Also there is no other alternative so they have that security.
And contrary to popular white-washed belief, there is very little to anything special in most copied designs.
So even if nobody ever sees my schematic or gerber files, they could still clone a lot of products if they just have someone spend some time with a multimeter on a device they buy.