Note: while theoretically this question "Only relates to one network site", the per-site Meta is gone (or not!), so I can't really post there, so I picked MSE.
On November 17th, 2022 Windows Phone SE was archived. That post was by an SE staff member, so I assume it is correct.
Presumably this was intended to include all of the per-site Meta for that site. After all, what would have been the per-site Meta link now redirects to an Area51 "Page Not Found" message, so I'm inferring the intent was to also remove the per-site Meta.
It appears one post was missed. All of the per-site Meta is gone... except one question that remains? None of the rest of that child meta seems to remain, per Google. In case SE removes it, here's a Wayback Machine link for future readers of MSE.
Why is that one post remaining while the entirety of that per-site Meta is gone?