The URL provided is just a page UUID with some parts deleted, not "404.html" or whatever. So it really is a "legitimately not found page", but would be hopefull

The URL provided is just a page UUID with some parts deleted, not "404.html" or whatever. So it really is a "legitimately not found page", but would be hopefully be flagged as "spike in 404 errors due to dead link [...] on news.ycombinator.com" by a reasonable CMS.