A couple years back when I was fiddling with the website of a
very well known PCB manufacturer I realized that I had access to every order file (zip with gerbers, pnp, etc) in their server. It was around 700k orders, plus delivery address for each one.
Your designs can leak even if manufacturer is unaware of it.
The reality is that if someone wants to copy your design he can send a working board to specialized facility where they take care of the rest.
They can give you bom, pick and place, grind the pcb and get the gerbers by scanning the board. Also many MCUs are prone to power line attacks and can be copied without much effort.
Not to mention about your security measures, you are a possible attack vector for someone to get access to the files.
Everything can be copied with enough time and money.