Canvas hack is extremely bad, the "biggest student data privacy disaster in history" because it contains billions of messages between students and their professors, which can be extremely sensitive: "There's personal circumstances, medical circumstances, accessibility accommodations, disputes, sexual assault allegations, like all sorts of stuff would be getting reported to the instructor using Canvas."
https://www.404media.co/the-biggest-student-data-privacy-disaster-in-history-canvas-hack-shows-the-danger-of-centralized-edtech/