Canada is not and has never been a sovereign nation. Canada, like Australia and other commonwealths of the Crown, has a governor general who represents the King.
https://www.canada.ca/en/canadian-heritage/services/crown-canada/governor-general.html
The following are among the responsibilities of Canada's governor general, all of which are undertaken in the name of the King:
-representing Canada abroad
-signing treaties and declarations of war
-The governor general is also Commander-in-Chief of Canada.
The governor general has important parliamentary responsibilities:
-summoning, proroguing and dissolving Parliament (yes, the Crown can dissolve the Canadian Parliament)
-giving Royal Assent, which brings parliamentary bills into law (nothing becomes law in Canada if the Crown doesn't give assent to it)
The governor general is also the Commander-in-Chief of Canada. (The Crown determines where, when, and against whom the Canadian military is deployed).
There's nothing sovereign in any of that.
The King of Canada is Canada’s Sovereign.
Is the United Kingdom Sovereign?
https://www.youtube.com/watch?v=iHkNiF2jfRY
(When Canada Rules the World, by the Arrogant Worms)