Why is the U.S upset about Mexico’s energy reforms law?

Mexicos President Andrés Manuel López Obrador is currently trying to make Mexico energy independent, and the U.S isn’t happy about it.

Why is Mexico voting for energy reforms?

Mexico may have given private and foreign firms too many incentives. They received preferential treatment in pricing and purchasing and didn’t have to pay the state-owned utility.

Why is the U.S unhappy about the energy reforms? see here.