I don't like how this story resolves the mysteries.
Part of the fun of a whodunnit is that the audience gets to participate and try to guess the culprit before the author reveals it. One of the most entertaining things about detective/mystery stories is when you get to figure it out beforehand because the author did a good job at presenting the information.
This is a bad example of that kind of story. The culprit's identity was pretty much an asspull, there was no way for the reader to know all the stuff mentioned in this chapter before the MC revealed it.
And yeah, you could tell me "this isn't that kind of story, it's about a physic MC solving impossible cases so you won't be able to figure it out" but it's certainly written and presented like one. What's even the point of trying to give us hints if the answer is going to be "this rando did it"?
