> Even the German government might have done it in a "burn the boats" strategy.
I would prefer to assume governments are somewhat rational actors, who at least try to act in the interest of the own country.
In this case, the biggest loser from destroying NS1 and NS2 is Germany, second-biggest Russia and the rest of the Europe, sorted descending by the dependency on Russian gas.
As for the winners, we have the USA and Ukraine as biggest immediate winners, and indirectly and in the long-term India, China, Arab countries, ...
Ok, what if NATO collectively (or at least the affected members) decided to destroy the pipeline in a show of resolution?
Let's say secret negotiations are ongoing (it would be surprising if they weren't) with Russia regarding a winter ceasefire. Russia annexes the occupied regions to force the hand and be in a better position, then offers gas in exchange of no NATO military help during the ceasefire.
NATO rejects the offer and blows the pipeline to show it is off the table.
This is a valid conspiracy.... when it gets cold, people will protest, and demand that their government sits down with putin and make a deal... with the pipes blown, the government can say that they can't do anything, and that it's not their fault.
I don't think Russia had interests in doing it, unless it is for some internal power play.
edit: or plausible denial when they won't send gas to Europe this winter. But do they even need the deniability at this point?