Goes without saying, but if you send your PCB design and BOM/CPL files to either JLCPCB or PCBWAY, don’t believe your IP will remain secure.
I use them often for test jigs and the like, where its so esoteric to my application I couldn’t care less if these designs start popping up on Aliexpress.
But if you are wanting to keep your design Commercial in Confidence, I’d be looking at other options.