Difference between leaving a fandom and actively fangirling or fanboying in Korean
탈덕·덕질
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.
덕질actively fangirling or fanboying
덕질 means being a very active fan of someone or something you love, like a singer, actor, character, or sports team. People use it when they watch videos, collect goods, go to events, or talk excitedly about their favorite thing. It is casual slang, so it is common in daily conversation but not very formal.
The difference
덕질 means doing fan activities, like collecting goods, watching content, or posting about your favorite. It is about being an active fan, not leaving the fandom.