app\Certificate::isExpiringOrInvalid PHP Method

    public function isExpiringOrInvalid()
    {
        $ed = $this->getExpirationDate();
        if (!$ed) {
            // invalid
            return true;
        }
        $interval = (new \DateTime('now'))->diff($ed);
        // LE certificates gets 90 days to expiry
        return $interval->d < 15 || $interval->m < 2;
    }