Currently, when a recurring event is created, Canvas sends a separate notification for each occurrence of an event.
For example, I just got the following notification:
There's a new event scheduled for Homeroom that you should be aware of:
from Feb 6 at 1pm to Feb 6 at 2pm
Since we will have On-Site PE 4 days a week pretty much every week from now until the school year ends in June, this means that I have 166 new messages in my "Canvas Notifications" folder at the moment, and most of them are this exact message with a different date. (I also have a few messages for unrelated things that I actually need to do something about, which means I have to wade through all of this clutter one by one.)
A single message stating something like:
There's a new recurring event scheduled for Homeroom that you should be aware of:
Between February 6th and June 12th, Every Tuesday from 1pm to 2pm
would be much more helpful.
I don't want to turn off Calendar notifications, because they are very helpful except on the few days when our Office Manager sets up the recurring events for each term.