https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206271
With a build, now all the links are the same, and there is no differentiating between an old security announcement, and a new one. All the files are in the new location, and accessible. All generated links point to the new https://www.freebsd.org/security/advisories/
Here is the newly rendered page:
https://people.freebsd.org/~jgh/files/htdocs/security/advisories.html