It was rushed AND low quality.
I don't want to harp on the quality aspect too much, there are a ton of small anime studies that lack the budget, personnel and time to make something like Frieren in terms of production value, but that is no excuse for rushing things. The ascendence of a bookworm anime is, imo a great example of making the most of what you have, but in this case it very much felt like they were just "going through the motions" and the cherry on top of this rotten cake is that the fact there was an adaptation already will make it 1000x harder to do a reboot/remake of it :/
Pretty sad situation overall, was hoping the anime could skyrocket the popularity of the manga & ln, but it very much had the opposite effect.