The word is in entertainment a lot. Outside the context of slavery, it still triggers me. For example, I'm watching a show called Gyeongseong Creature, and characters keep saying "Master Jang." (A protagonist.) He's an ultra rich guy who owns a pawn shop. He's constantly acknowledged as if he's an authority figure. I don't have enough context about Korean culture to understand when and why people get the label "Master." It just sucks to hear.
It would help if hearing "master" and observing severe sucking up didn't feel so visceral.
Take out the sucking up part, and in most cases, it's used to signify someone is a master craftsman builder or a master of their specific craft, or a leader in the field to which others come to them to learn from. Think of it as a PHD professor in the example you gave.