Why did the Austrian Republic pass the Habsburg Law in 1919?

The Austrian Republic passed the Habsburg Law on April 3, 1919, primarily because the last emperor, Charles I, had not abdicated his hereditary titles or those of the Habsburg dynasty, despite his November 1918 proclamation renouncing his share in state affairs.1

To secure the new democratic republic and prevent potential monarchist restoration efforts, the National Assembly enacted the law to banish all members of the Habsburg family from Austrian territory unless they formally renounced all dynastic pretensions and accepted the status of private citizens. Additionally, the law mandated the forfeiture of Habsburg property rights in Austria.1