1. What does it mean?
탈덕 describes leaving a fan interest or fandom rather than merely taking a temporary break. It is commonly paired with 하다 and contrasts with 입덕, becoming a fan.
Also written or said as 탈덕하다, taldeok
2. The nuance
It does not necessarily mean hating the former favorite or abandoning every hobby. Interest may fade quietly. Keep it distinct from 휴덕, and let a person describe their own decision instead of assigning the label to them.
3. Examples
“그 시리즈는 탈덕했지만 예전에 좋아했던 기억은 남아 있어.”
I'm no longer a fan of that series, but I still have good memories of enjoying it.
“요즘 글을 안 쓴다고 탈덕한 건 아니야. 그냥 바빠.”
Not posting lately doesn't mean I've left the fandom. I'm just busy.
Sources
DukPlace: K-pop fandom glossary
References support the meaning and usage. Example sentences are written for NoCapWiki.