In 2015, the US lifted its ban on exporting domestic oil. Since then, US domestic pricing has been linked to the global price.

This means that "domestic production" does not mean what you imply (which is "domestic production that must be sold in the US.") If US producers can make more money selling 100% of domestic production overseas, they will do that.

This is not price-fixing, it is the predictable outcome of a market design where US drivers bid against Asian airlines for petroleum products.