I definitely think the whole manga spent maybe the first few chapters, tops, meaningfully pretending to be a "detective story" in terms of genre and structure (rather than simply the subject), and even in those chapters it was only pretending, as most of the apparent clues in the first case also ended up being loose ends, red herrings or unsolvable. I count it as a bit of a failure for the manga as a whole, but don't even bother worrying about it with each new chapter, as that particular matter has been a dead horse since literally (checks calendar) 2020.