Many sculptures from antiquity were defaced during the early Christian period. During riots, Christian mobs would smash the noses off of ‘pagan’ sculptures, as they usually depicted pagan gods, or emperors, and depending on the sect, any depiction of a person could be considered ‘graven’.
The hotbed of Christian zealotry was Egypt. Throughout its time as a Roman, and then ‘Byzantine’ province during its early Christian history, the province proved practically unmanageable due to its Christian theological riots, with the majority of the population not following Constantinople’s doctrine and theological orders.
This Roman bust of Germanicus at the British Museum was defaced - nose smashed off - during a riot that would have taken place in late antiquity in Egypt, so, 400-500AD [also, note the cross etched into forehead]
Probably the most known example of this is the destruction of the Alexandrian Serapeum, a vast temple complex in Alexandria, Christian mobs tore the temple apart, destroying and looting, tearing it down brick by brick.
Another example, outside of Egypt, is the Nika Revolts in Constantinople. On its creation as a co-capital of the Roman Empire, an unfathomable amount of art and sculpture was brought to adorn the New Rome, and during the revolt, for the most part this cream of the classical crop was destroyed, again, by theological mobs.
After Egypt’s conquest during the Arab-Islamic conquests, this practice would have continued. In fact, theologically, many of Egypt’s Christian sects were more in line with Islamic theology than what became mainstream Christianity in both ‘Orthodox’ and ‘Catholic’ doctrine.
Basically, if you want to know what happened to sculptures from antiquity, Abrahamic faiths happened to them. We divorce classical and ancient sculptures from their meaning - we see them as history or art, but to the new faiths, they were graven images, they were pagan, and they were destroyed or defaced.