The tap was already turned off. I think everyone at the time understood Biden's comments to mean the nordstream 2 pipeline wouldn't be operational because of diplomatic pressure on Germany. And that's exactly what happened, Germany decided not to certify it and it was left functional but not pumping any gas (the current leak was likely just enough to keep the line pressurized).
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.
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.