We dont know who is doing this, but it feels like a large nation state. China or Russia would be my first guesses.
US or UK would be my first guesses. They need a contingency plan to shut down Internet and introduce martial law when dollar-based financial system implodes and trillions of dollars and pounds in banks evaporate.
The Sterling is already everaping at the moment. Its value has dropped over 20% in the last few months.