I think many people use the word banana to refer to people who come back from foreign countries. Why?

In the west, the term "American-born Chinese" mainly refers to the fact that after the yellow race immigrated to the west, their next generation was born and lived in the west, and their living habits and ideology have been "westernized", although they still retain the color and image of the yellow race. Banana skin is yellow, but inside it is white, so it is used to describe the second generation and their descendants of yellow immigrants who have been westernized. This is the so-called "American Chinese". It's not that accurate. Although some of them came back from studying abroad, they only lived abroad for a period of time, and their living habits and ideology have not been completely westernized, which means that the "core" has not been completely "white", so it is not accurate to compare them with bananas.