The One UI V4.0 update that you received was pulled by Samsung shortly after it was released.
There was a Google Services compatibility issue for some users.
Yes Canada receives monthly Security Patch Updates. Just hold on to your shorts, Samsung was busy fixing the issues with the initial release of One UI V4.0 for the S21 series & other devices.
Monthly Security Patch Updates are often towards the end of the month, for the previous month. That's just the way it has been.
I am here in Canada as well. It is now the end of March and I'm still on the Jan 1st security patch? Did they have issues with the last 2 updates I wonder? I'm having all sorts of issues with my s22 ultra, mostly reception issues and I'm hoping the next update fixes it. It becomes unusable at times. Reception will drop from 5 bars to 1 and back to 5 and then back to 1. It's all over the place