沼にハマった。
I've fallen deep into the hobby/fandom. (lit. "stuck in a swamp")
✦ AI pragmatic read · suggests Casual
A self‑deprecating, colloquial expression used among friends or peers to admit being engrossed in a hobby, implying a casual, non‑formal tone.
A starting point, not the final word — open the entry to add your own note if you'd explain it differently.