I am flying YYZ-YZR on August 20th. Originally, I was scheduled to depart YYZ at 16:00 arriving in YZR at 16:56. About two weeks ago I received an itinerary change email, which included massive changes to my return flights (called AC and made some flight changes). I originally assumed AC had cancelled one of the three daily flights to YZR, but this is does not seem to be the case anymore as FA is showing three daily flights still.

Essentially, I was placed on a slightly later flight to YZR on the 20th (JZA7985) when I was originally on JZA7983.

Why the heck would AC move me off my original flights when it seems like they had zero reasons to do so?