My friend worked for government and you do indeed get a top-up but I believe you have to return to work for a minimum of 2 years otherwise you have to pay it back. But don’t quote me on that!
Also, Canadian mat leave is indeed amazing! The max amount (if you make $55k or above) is $2100 a month before taxes. After tax it’s around $1850. That’s not a crazy amount, but if you do it right, it should be enough to cover rent and bills (if you have a partner to split that stuff with), which is great! Plus your employer has to legally keep your job for you, so you will return to the same job after a year.