Russia has a motivation to kill the pipelines now, to increase gas prices now, as NS1 & NS2 are NOT the only paths to get gas to the EU. Since they are already down for "maintenance" (and we actually know some maintenance is needed), it would be a good tactical move to kill the possibility of NS1 & NS2 delivering gas, increase focus on the crisis now, and hope that this scares the EU into stopping supporting Ukraine.
Norway also reported drone sightings on their oil & gas fields. It would be very tactical for Putin to start taking out all EU supplies as much as practical, since he obviously cannot win on the battlefield.
My feeling is that this will backfire in the current information environment, in the short term only enraging the victims by making clear who is the enemy creating the misery, and in the long term giving politicians justification to say that Russia is an unreliable supplier. It can only work as long as there is a mystery about who is taking out supplies, and if any other facility than Russia's own are taken out, everyone knows that the culprit is Russia.
Also, Russia is so good at this that they have a word for it: "provokatsiya" or "provocation", 'A political event staged by an intelligence service on behalf of its government in order to accomplish some political goal. '.[1]
Russia also has extensive submarine capabilities and ports on the Baltic Sea. [2]
Means, motive, opportunity. That's my bet right now, given limited open source information.
[0] https://oilprice.com/Latest-Energy-News/World-News/Norway-In...
[1] https://en.wiktionary.org/wiki/provokatsiya
[2] https://www.researchgate.net/figure/Russian-Ports-in-the-Bal...