AC120 YVR to YYZ today (Dec 12)

Received an email yesterday (Dec 11) of an advisory that there was low ceilings and visibility for YYZ and that my flight may be affected. AC offered me to change my booking for free.

After that they changed my flight number and mentioned there was no change of departure time. This morning (Dec 12), AC states flight will be delayed 4 hours because the incoming flight is delayed. Is it possible for me to confirm that being the reason?
At the time of writing it's now being delayed an extra 30 minutes due to another aircraft change.

Time to figure out if they can book me on an earlier flight or if I can book 1 through my CC flight delay insurance..