From AP:
Pope Leo XIV’s election as the first U.S.-born leader of the Catholic Church elevated him to the extremely rare, and legally thorny, position of being an American citizen who now is also a foreign head of state. Born in Chicago as Robert Prevost in 1955, the new pope for the past decade has held dual citizenship in the U.S. and Peru, where he spent time as a missionary and bishop.
As Pope, Leo serves as leader of both the Holy See, the governing body of the Catholic Church, and Vatican City, an independent state.