2. EU is trying to stop being reliant on Russian gas, so far it isn't fait accompli.
3. Based on 1+2 we could assume someone wants to push EU as far away from Russia as possible as fast as possible(regarding gas supplying, to be clear)
So again, who profits and has the means to do accomplish such feat: 1. USA: very vocal against NS2, wouldn't be affected by such destruction of foreign infrastructure, stands to gain when adversaries lose. Germany becoming dependent on US gas is a massive bonus. Imagine being able to control EU's largest economy on a whim.
2. Russia: assuming they would want to destroy the pipes, and not the much easier land infrastructure, why not let the world know about it ASAP?
3. Eastern Europe: only Poland has the means and maybe motivation to do so.