As a faculty member teaching asynchronous classes, I rely on "submission comment" notifications to communicate with students. For example, because Canvas won't register that late responses have been added to a discussion post, I request that students leave me a note in the comments when they have submitted late responses. This way, I receive a link to their submission and can update their grade right away.
Sometime in the last couple of months, Canvas has added "submission annotation" notifications, which are lumped together with the "submission comment" notifications. This means that every time a student leaves an annotation for another student in a peer review, for example, I get a separate notification email for EACH annotation. Often, this means getting dozens and dozens of emails in a short period of time, as each student might leave 10 or 12 annotations on a single assignment, times 3 essays per student, times 75 students!
Not only does this create a distressing amount of emails, these notifications have a very similar subject line to the "submission comment" notifications, and they are difficult to filter out via my email client, or to delete in bulk without potentially losing the notifications I DO need to see. I would love for these two different kinds of notifications, which are useful in very different ways, to have their own on/off toggle, rather than be lumped together.