Canada Border Services has provided a statement regarding the current and upcoming changes at the Canadian Border crossings. Currently a negative molecular COVID-19 is one of the requirements, travel and contact information, 14 day travel history, quarantine plan, vaccine information and a COVID-19 self assessment. On November 30th travelers who enter the United States and return to Canada within 72 hours, are not required to have a negative COVID-19 test, however any trip to the United States longer than 72 hours will require a negative COVID-19 test. Border officials also add that the ArriveCan app must be filled out regardless of the duration of your trip.
https://travel.gc.ca/travel-covid/travel-restrictions/wizard-start
https://travel.gc.ca/travel-covid/travel-restrictions/exemptions
https://www.canada.ca/en/public-health/services/diseases/coronavirus-disease-covid-19/arrivecan.html