The Nord Stream bombings immediately sent gas prices soaring, bolstering Russian profits and causing a panic in Europe, particularly Germany, about an imminent gas shortage during the upcoming winter. Russia was the direct beneficiary of NS being blown up at the time it happened. And when the pipelines were blown up, there was no gas flowing through them anyway, plus very little prospect of gas flow resuming anytime soon. Aaand it was the time when Ukraine was on the offense and Russia was in retreat, so Russia had a huge incentive to stop the Western aid by any means necessary.
So even if they didn't end up being the culprits, the general idea made perfect sense. Certainly more sense than your claim that Ukraine was bombing the Zap NPP in 2023, risking the contamination of 50% of its own territory, at a time when the situation on the battlefield was still a stalemate and there was no major international summit going on.
Doesn't make sense, was endlessly discussed
The construction costs of NS2 project alone was 10+ billion, Russia paid a chunk of that.
How many billion in profits would Russia gain exploiting the pipelines when eventually relations would be normalized.
Russia controlled the flow of gas which means there was absolutely no reason for them to blow em up.
They had absolutely no reason to blow up their own pipelines just like they have no reason to shell their own troops at Zap NPP or to fly a drone into the Chernobyl NPP.