A later news release Thursday indicated that Trump had decided to end the month-by-month cost sharing subsidies that help some people buy health insurance, CNN link. The president says that a federal court had ruled that these payments are illegal (Aug. 2 Washington Post opinion by Ilya Somin; Atlantic article ; Wikipedia: House of Representatives v. Burwell or Price). Insurance companies still have a legal responsibility to honor the subsidies but could drop out.
The president had to be reminded by Pence to sign the order, an event that had also happened in March.
Update: Oct 13
I'm already seeing people (who voted for Trump) saying on Facebook that their own subsidies, which they need for lifesaving medications. will be cut. What's next, personal gofundme's? Are social media friends supposed to become personal safety nets?