I thought Suzu was suspicious ever since the father was vindicated early on, since whomever it was that poisoned Chinatsu had to have access to the paraquat in the house. And the rabbits must have been killed by someone with a connection to the school, adding to my suspicion. Now the narrative's leaning pretty hard into that with the conflict with Akane, so it might be a bait and switch, unless the story's wrapping up soon.