To my understanding (I've been closely watching this as part of a joint weather-equities/commodities venture I'm in), the U.S. panicked and began flooding the market heating oil market starting late 2022 with extra supply from our SPR.

This was not widely discussed or even well understood in local media (shocker), but the prevailing thinking is that this occurred to stem outrage in the Northeast U.S. as oil prices soared. It's also *just* coming out now that U.S. based shale production has been massively underwhelming for months, despite the lavish numbers coming out from the EIA. This would further bolster the idea that SPR releases were targeting demand in the Northeast markets.

I believe both sweet & sour crude stored in the U.S. Strategic Petroleum Reserve is of quality, however it's entirely possible that a) it loses this quality the longer it sits in storage and b) you're ultimately seeing the results of this.