Article on diesel fuel prices and supply in the New York Times this morning:
https://www.nytimes.com/2022/11/10/business/energy-environment/diesel-prices-inflation.html
As others have opined, there are multiple reasons for the current squeeze on supplies and rising prices. The war in Ukraine and halting imports from Russia is one factor. Another major reason is insufficient refining capacity, which is sobering (for those who buy diesel fuel) because more refineries can't be built or brought on line very quickly.
I miss the proverbial 'good old days' of only about 20 years ago, when my friends with gas engine boats would rib me how 'unfair' it was that diesel was a buck a gallon cheaper than gas. I don't think I'll see that again in my lifetime.