With Noctua I highly doubt that is the case given their track record for quality overall and all other information available around their design and engineering process. As far as I know based on all the information I have seen all the design and engineering is done in Austria. They also have a track record of only releasing things once they are satisfied something performs within their standards. Something that would be next to impossible when solely relying on external fabs and process engineering.

They also utilize different manufactures afaik (historically Taiwan, but also China these days) meaning they need to have pretty solid in house knowledge and expertise to make sure different factories produces similar results. When they first started utilizing Chinese factories people noticed visual differences and were worried about that. But Noctua at the time claimed that they made sure that performance was still the same. A claim that was put to the test by various review outlets at the time (I want to say gamer nexus did a big piece about it?) and confirmed to be true.

Having said that, if you do utilize external factories you automatically are making use of their process engineering to some degree as well. But, and this is difficult for many people to understand, that isn't a binary thing either. You can entirely rely on the factory to basically do everything for you and just send feedback on iterations but you can also work closely with them and actually get involved in the process itself.