Translation differences. Different people have translated this manhwa on here, so the ones at the very bottom are different from the official being posted and different from the translator posting a day earlier than the official. In the raws Yeomin calls him “Taeseo ssi”, which basically means Mr. Taeseo. The official probably has it translated to Mr. Yeon because it’s more common to call someone by their last name in English, when “Mr.” is in front. I hope that made sense I’m very tired as I’m writing this

Why does he call TESEO at the beginning of the manhwa yeomin and then suddenly become Mr. Yeon?