A Jew is not allowed to steal from a gentile, but if a gentile shopkeeper unwittingly gives a Jewish customer more change than was due to him, the Jew is under no obligation to inform the gentile and can thereby profit from the shopkeeper’s mistake, though this wouldn’t be allowed if the shopkeeper were Jewish.[6]
https://www.etzion.org.il/en/philosophy/issues-jewish-thought/rabbinic-thought/talmudic-attitudes-gentiles-2