It's not clear to me if dropping support for this functionality was intentional.

Chain of events:

- #21689 removed test coverage due to a misunderstanding due, I believe, to this functionality being generally supported by all platforms except macOS which does not and returns a different format
- #21756 removed support and caused this regression
- #21690 restores the test coverage that would have caught this regression

Currently, neither the test coverage before #21689 nor the coverage restored by #21690 pass since the merge of #21756.

return false;
    if (IsInternal())
        return false;
    if (IsIPv4()) {
        const uint32_t addr = ReadBE32(m_addr.data());
        if (addr == INADDR_ANY || addr == INADDR_NONE) {
            return false;
        }
    }
    return true;
}
/**
 * @returns Whether or not this network address is publicly routable on the
 *          global internet.
 *
 * @note A routable address is always valid. As in, the set of routable addresses
 *       is a subset of the set of valid addresses.
 *
 * @see CNetAddr::IsValid()
 */
bool CNetAddr::IsRoutable() const
{
    return IsValid() && !(IsRFC1918() || IsRFC2544() || IsRFC3927() || IsRFC4862() || IsRFC6598() || IsRFC5737() || (IsRFC4193() && !IsTor()) || IsRFC4843() || IsRFC7343() || IsLocal() || IsInternal());
}
/**
 * @returns Whether or not this is a dummy address that represents a name.
 *
 * @see CNetAddr::SetInternal(const std::string &)
 */
bool CNetAddr::IsInternal() const