Difference between leaving a fandom and becoming a new fan in Korean
탈덕·입덕
탈덕leaving a fandom
탈덕 means leaving a fandom or stopping your support for someone or something you used to love. People often use it for idols, singers, actors, or characters when they are not a fan anymore. It is casual slang, so you will hear it more with friends and online than in formal situations.
입덕becoming a new fan
입덕 means becoming a new fan of someone or something, like a singer, actor, drama, or game. People use it when they start to like it a lot for the first time. It is casual slang, so you will hear it in friendly conversations and online.
The difference
입덕 is the opposite direction. It means you start liking an idol, actor, or character, not stop being a fan.