A long time ago about 2016 ( six years in seo is a long time ) , Google removed PR from Public View.
Meaning no one can provide you with Google's PR for a particular site, except Google of course, but hey
they removed it so you can't see it.
That site can only provide you with numbers that it generates to approximate what they think the PR
In my opinion, Ahref's and Moz provide the most accurate approximations of PR.