I'm not entirely sure what you're trying to say. The patent grant applies to Facebook's patents (if any) on the tech used in React.
> I think the patent grant applies to everything you make
Yes, if you have a patent grant from using React, it would be a defence from claims that things you have written that do not use React violate patents included in the grant.
I just re-read it, you're correct. It only covers React
> For avoidance of doubt, no license is granted under
Facebook's rights in any patent claims that are infringed by (i) modifications
to the Software made by you or any third party or (ii) the Software in
combination with any software or other technology.
