https://issues.dlang.org/show_bug.cgi?id=24493

          Issue ID: 24493
           Summary: FreeBSD_14 version identifier missing
           Product: D
           Version: D2
          Hardware: All
                OS: FreeBSD
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: issues.dlang@jmdavisProg.com

On FreeBSD 14, this program

---
void main()
{
         version (FreeBSD_14) pragma(msg, "14");
    else version (FreeBSD_13) pragma(msg, "13");
    else version (FreeBSD_12) pragma(msg, "12");
    else version (FreeBSD_11) pragma(msg, "11");
    else version (FreeBSD_10) pragma(msg, "10");
    else version (FreeBSD_9)  pragma(msg, "9");
    else version (FreeBSD_8)  pragma(msg, "8");
    else static assert(false, "Unsupported version of FreeBSD");
}
---

prints out 11, so FreeBSD_14 is not being defined correctly. Presumably, it just hasn't been added yet.

--