I've heard rumours from people-in-the-know that Giphy had some Hollywood connections and got a backroom covenant-not-to-sue from most, but not all, of the major

I've heard rumours from people-in-the-know that Giphy had some Hollywood connections and got a backroom covenant-not-to-sue from most, but not all, of the major rightsholders - I assume their argument is that widespread use of classic movie GIFs doesn't harm sales, and they'd be in a position to encourage people to use GIFs from current releases - which in-turn drives box-office revenue, so that's the likely explanation.