I still can't explain why Putin would shoot himself in the foot like this. Germany was going to buy Russian gas this winter in rubles and Putin needs the money Now they can't!
Six points that may be helpful:
(1) As part of EU sanctions against Russia following the latter's attack on Ukraine,
Germany already shelved Nord Stream 2 pipeline in February.
(2) In response to the West's sanctions,
Russia halted in September gas supplies to Europe using Nord Stream 1 pipeline. On a superficial analysis, this is effectively Russia 'shooting oneself in the foot' but also a classic shock and awe tactic, demonstrating Russian power and Europe's dependence on Russian gas. The halting of Russian gas has been a major sting to Europe preparing for the winter while Europe is busy securing alternative energy supplies such as Norwegian gas.
(3) Sabotaging Russia's own pipelines is not a new tactic
as demonstrated with the case of Georgia in 2006.
(4) By sabotaging the Nord Stream pipelines after having already halted the gas supply Russia (read: Vladimir Putin) isn't sabotaging a commercially lucrative asset. Russia has already concluded that it's energy cooperation with Europe is over.
(5) By sabotaging the pipelines Putin sends the following
signals to Europe and the West in the context of humiliating recent losses in Ukraine (Kharkiv, Lyman and Tors'ke) which is armed and supported by the West:
(a) Shock and awe: Russia is still powerful and can inflict significant damage internationally. Don't underestimate Russia.
(b) Warning: Russia is capable of sabotaging also the Norwegian pipelines should Europe choose to rely on it while continuing to arm Ukraine.
(c) False flag for domestic war-justifications: Citizens, the US is sabotaging and attacking Russian assets! This justifies continuing and escalating the war in Ukraine as well as the recent partial mobilization of Russian reservists which has shocked many citizens.
(d) Reminder of dependency on Russia: Europe, unless you get your act together quick in securing alternative gas, you're guaranteed to have a cold, cold winter. This was your choice and your mistake. Not Russia's.
(6) What seems irrational to the common spectator of these events may make sense to Putin. Also, to dismiss that Putin is behind the sabotage by appeal to 'rationality' is a poor argument when assessing megalomaniac dictators that have demonstrably made multiple irrational decisions recently which have ended up hurting Russia.
Most of the above analyses of 'why is it in Russia's interest to sabotage its own pipelines' are available from various think tanks, expert assessments and news outlets in Europe.
From a 'mainstream' European perspective (I'm a European) it's almost self-evident Russia is behind the sabotage. Some Europeans disagree, including on MB, but imho they're susceptible to Russian propaganda.