My theory is that Putin ordered it. He recently made two major escalations, mobilization and annexation, that greatly decrease the odds of a peaceful settlement and increase the odds of him being overthrown internally. This move undercuts the leverage a new leader would have after a coup, since it will be harder to get gas flowing again following a truce.

Putin seems to be staking his entire regime on this war and likely feels that upping the stakes is to his benefit. His odds of winning a conventional military victory are looking more and more slim, but ratcheting up the risk might get the West to back down, at least in his mind.