The scientists didn’t actually read all 1,140,328 discussion-board submissions written by 16,791 students between the fall term of 2021 and the winter term of 2024.
"I think we can infer this is due to the availability of AI because what other things would produce these significant changes?”
Yu and his research colleagues didn’t interview any of the students and cannot say for certain that the students were using ChatGPT or any of its competitors, such as Claude or Gemini, to help them with their assignments
If this had been actual research this might be an interesting result, but it's not. It's pure speculation without a shred of verification.