You can have all of the amazing technical details you want in your story---perfect spelling, perfect prose, and an answer to every single question---but to me, none of that matters when the core story itself is trite or boring. It's why I could never get into the top-ranking novels on Honeyfeed.
With Miasma, 99% of its issues come from occasional spelling mistakes, which, because they're really consistent, I assume are due to the author having English as a second language. Some chapters felt a little haphazardly written, but they were nonetheless understandable.
The prose is mostly great, and the pacing is incredible... aside from a slightly abrupt ending (albeit it was incredibly thematic).
Miasma does many things right: a small and focused cast, an interesting world, great foreshadowing, good action, good sense of tone, and the ability to avoid common isekai/fantasy pitfalls. It's clear it is a passion project, and not something written to be a safe entry in the isekai contest.
Miasma's world is portrayed incredibly well, which was highly elevated by the protagonist's limited perspective. There are no massive lore-dumps, and things like the religions are explained well enough for the reader to not only understand, but to also be able to come to their own conclusions. I was fully engrossed past the first few chapters. It's really difficult to explain without spoiling anything, but there is an interesting moral conflict between the world's religions that the protagonist remains torn between until the bitter end.
Miasma is absolutely worth the read, and it is a gem of pure originality on this site.