The old grant terminated if, among other things, you argued that any Facebook patent was invalid or unenforcable. This meant that if Facebook sued you over an unrelated patent, you couldn't defend yourself without the React patent grant terminating.
The new grant specifically exempts any counterclaims; you can't lose your patent grant just because you defend yourself. You can still lose it if you sue Facebook over unrelated patents.
The old grant terminated if, among other things, you argued that any Facebook patent was invalid or unenforcable. This meant that if Facebook sued you over an unrelated patent, you couldn't defend yourself without the React patent grant terminating.
The new grant specifically exempts any counterclaims; you can't lose your patent grant just because you defend yourself. You can still lose it if you sue Facebook over unrelated patents.