Thank you for posting this! I am currently on a 3 week trip to the United States to visit some family and I had not noticed or forgotten this detail.Incorrect- you do have to notify IRCC if you leave Canada for more than 2 weeks, and is explicitly mentioned in the application.
This is how it goes- until the moment an applicant is called upon for the oath, checks are done from a criminality/security (also called as prohibitions).
https://www.canada.ca/en/immigration-refugees-citizenship/services/canadian-citizenship/become-canadian-citizen/after-apply-next-steps.html
Please see here where it says you have to notify if we leave the country for over 2 weeks in a row.