We've been here before. The patent protection used to go one-way, but now goes both ways after the issue was raised. Most open-source code comes without patent grants of any kind, so use would automatically infringe which is a far worse situation than here. More pragmatically, few companies could actively pursue a successful patent war with Facebook because the company would run out of capital before the suit was settled. That said, I haven't seen evidence that Facebook actually owns any patents related to React which makes the grant somewhat moot.

> Notwithstanding the foregoing, if Facebook or any of its subsidiaries or corporate affiliates files a lawsuit alleging patent infringement against you in the first instance, and you respond by filing a patent infringement counterclaim in that lawsuit against that party that is unrelated to the Software, the license granted hereunder will not terminate under section (i) of this paragraph due to such counterclaim.