It's very correct - but the implications must not be clear.
In the CIELAB space (read: a scientific space), JND is 2. (3 is color science version, but a minor quibble)
In OKLab space, we'll say it's the same, and then account for normalized lightness.
Oklab's lightness isn't CIELAB's lightness, neither are their dimensions the same, so it's like saying "when we measure in kilometers, a Just Noticable Distance is 2 meters. Miles is scaled differently then normalized, but we'll just say it's 2 yards." (and that's being too kind, in practice, 2m ~= 2 yards, and I don't want to give the impression it's a simple linear scaling difference. The example is meant to communicate they're different dimensions entirely)
> i assumed (wrongly?) that the CSS color specification would be accurate. or, at least, accurate enough to not make heads spin. (any ideas on why w3 got it so wrong? or why they would use OKlab at all, if it is as utterly awful as you imply?)
The thrust of my comment isn't that Oklab is so awful it should be banned, in fact, it's specifically mentioned as better than the incumbent. However, continued reusing of color science terminology, and people assuming that it then applies, is both remniscent of HSL and may worse intellectual poverty for software engineers, even the well-intentioned and studied, as it sounds unobjectionable at its face, but would be batshit insane if applied to synonymous areas of science that affect daily life (ex. distance)