Earlier quoted context omitted.
Common theme I've heard here (Kyiv, Ukraine) is that this sabotage is in Putin's direct interest. There are rumours of political infighting among Russia's leaders and that there are several factions trying to seize power, however since there is no clear winner, those guys need powerful allies, EU being a very important one. The idea is that Europe really wants to buy Russian gas, but not from Putin, so if Russia some…
Russia could have just turned off the tap. The sabotage ensures Europe can't back off from the US sanctions now. Wrecks Germany's economy, thereby eliminating a rival. VW et al are already talking about moving production to the US. And Biden promised to take care of NS 2 back in February itself. https://youtu.be/OS4O8rGRLf8
I also don't think the US sees Germany as a "rival" in this way at all, they are a strong trading partner.
The motivations are not that clear for any actor really. Someone wanted to burn a potential bridge between the EU and Russia, but it's not clear to me why the US would want to lose their biggest carrot (immediately dumping cash into Russia if sanctions were lifted and gas could be bought), or why Russia would want to lose a pipeline they invested so much into, sitting there and just tempting the west to Germany to ease sanctions.