Did you know it's called the View Transition API (and not the View Transitions API [plural])?
Now MDN knows too (https://github.com/mdn/content/issues/37265) so there's no reason to keep using the wrong name.
Learn about this and other VT misconceptions in this post: https://developer.chrome.com/blog/view-transitions-misconceptions
To be clear: it's only when talking about the API when you should be using the singular form.
It's still perfectly fine to say things like “The site uses View Transitions” or “The View Transitions specification”.