The 7th and 8th centuries were a period of turmoil for byzantium. this period saw the loss of eastern provinces to conquest under the banner of islam. these events persuaded emperor leo iii that god was punishing the empire for its idolatrous worship of icons. based on this what did leo iii initiate?

Leo III initiated a ban on the use of images for worship

Leo III accomplished many military milestones which made him popular and also gave him the confidence to pursue his religious policies. By banning the use of religious images, Leo II provoked a century of conflict within the empire

Leo III an Isaurian in Syria and a Byzantine Emperor who initiates to formally prohibited the use of images. He is against the worship of images. Leo III establish a legislative reform that dealt with the destruction or attacking of the icons, monuments, and images. This reform called Iconoclasm.

so they can differentiate themselves from others as they saw themselves as the superior race. the star was basically a symbol that meant you are a less of a person than i am because of my race. the star was also degrading for those who had to wear it because they were aware of this and the nazis used the notion to make them feel less like a person.