You can build a list of potential suspects and their motives...

You can build a list of potential suspects and their motives quite easily, Wallaby. Key to this is to list only those countries which have the ability combined with the motive. Few have the ability - ie to mine a Baltic pipeline in a shallow sea surrounded by nations from NATO and the Russian sphere. The Swedes have the shallow sea diesel subs, but no motive. The Brits definitely could have, but they are up to their necks atm.
Russia, yes, could have done it. Why would they? Because the pressure to restart energy delivery to Northern Europe would be removed. It no longer functions. You won't let us repair it.
The US. To blame Moscow, and enforce removal of European dependence on Moscows gas.
The Chinese. To send a message to everyone about their new strength. And so on.
Whatever it is, whoever did it, it will effect the take up of EVs in Europe, by highlighting the delicacy of fossil fuel supply. Europe, like the US, has to rid itself of its dependence on a totalitarian regime to its East. Just as much as American has to confront another to its West.
And we at Sayona are right at the point of the spear, which has recently been sharpened even more.