If the numbers were all that is wrong, that'd be OK. But it fails to list all data -- so the only way to navigate to the missing PRs is to know their number, and manually inserting the right URL (or to go to another PR, and then edit the URL in the navigation).
Sorry, but I don't think there is any way this can be classified as "not actually a bug"
Sorry, but I don't think there is any way this can be classified as "not actually a bug"