>>12419103ah, i understand the sort of thing you mean.
the short version is that it was a moderately successful manga, so while it was still publishing the first arc got adapted into an anime that was very well received. as always, this lead many people to go read the manga while waiting on a season 2. during that time the manga concluded and everyone warned people who were waiting on the anime that there's a massive tonal shift coming and the story peaks on the second arc then slowly goes downhill though it's still probably 6/10 at absolute worst by the end.
well season 2 started airing this season. it was business as usual for about 3 episodes and everyone was loving it, then it randomly skipped the arc everyone said was the story's peak. after that the show covers the remaining 130 chapters of the manga in approximately 8 episodes. for reference the first season covered about 40 chapters in 12 episodes