Earlier quoted context omitted.
I agree with you, it generally makes absolutely no sense for Russia to be behind this (at least not the mainstream Russian state, I have my doubts about their internal unity). What's more, I find the timing of this incident odd, having happened just after the victory in the Italian elections of the far-right, who is somewhat ambivalent towards Putin. The only conceivable motivation I can come up with for Russia would…
>> it generally makes absolutely no sense for Russia to be behind this Of course it does - Poland is entirely relying on the Norway to Poland gas pipeline, if that goes then a country of 50 million people has no gas this winter. Blowing up the Nordstream was(to me) a clear signal that EU needs to be careful or the Norwegian pipelines are going up next.
What has Russia gained with this?