YouTube is a video sharing service that allows users to watch videos posted by other users and upload videos of their own. The service was started as an independent website in 2005 and was acquired by Google in 2006.
As far as a website that shows the most recent update, all I could find was this page, which basically just states that you can contact your dealer to update your CMU (infotainment system).
If you have Mazda connected services set up, it should be available over that connection. There is a menu to check for updates, I think it is under Settings - System. Mine is also at 11022 for 2021 CX-5.