Yên is also used as a masculine name in Vietnamese, alongside An. However, Yên is more common for females. So, I think that the "Gender" of this name should be changed from "Feminine" to "Feminine & Masculine".Sources: https://www.names.org/n/yen/about https://forebears.io/forenames/yen
Sources: https://www.names.org/n/yen/about
https://forebears.io/forenames/yen