Reservations have always been under US authority. They aren't under state laws. So we see Indian Casinos etc.
Domestic dependent nations status refers to the unique legal status of Native American tribes in the United States, recognizing them as self-governing entities that are separate from state governments
but under the jurisdiction of the federal government. This designation acknowledges the tribes' inherent sovereignty while also establishing a trust relationship with the federal government, which has a responsibility to protect tribal interests and provide certain services.
The United States holds title to approximately 56 million acres of land in trust for various Indian tribes and individual American Indians. This land, known as "trust land,"
is managed by the government for the benefit of these groups. These trust lands are generally exempt from state and local property taxes, and income generated from them is also exempt from federal and state income taxes.