My My is based on songs from S.E.S so that song makes sense to remind ya'll of older music and I agree that I don't know and Hush are in the same kind of sound category
i honestly don't know what makes me feel that way, but almost all of their title tracks, especially my my, 몰라요 and now hush, remind me of older songs, like idk the timeframe from the 70's till early 2000s, can't really put my finger on what exactly makes me feel that way, but i freaking love it. [2]