Same reason the US is going after Pix in Brazil. The world is decoupling from the US and the US is going to try to flex against it as it continues. Dollar dominance and the “exorbitant privilege” continue to erode (with the acceleration self inflicted). Also shrinks the TAM of these private US firms to only the US versus the world.
https://en.wikipedia.org/wiki/Exorbitant_privilege
https://news.ycombinator.com/item?id=48994782
https://news.ycombinator.com/item?id=48415854