icingaweb2/modules/monitoring/application/views/scripts/partials/downtime/downtime-header.phtml

<table class="action">
  <tr class="state <?= $stateName; ?><?= $downtime->is_in_effect ? ' handled' : ''; ?>">
    <td class="state">
      <strong><?= $downtime->is_in_effect ? $this->translate('Expires') : $this->translate('Starts'); ?></strong>
      <br>
      <?= $this->timeUntil($downtime->is_in_effect ? $downtime->end : $downtime->start, $this->compact) ?>
    </td>
    <td>
      <small>
        <?php if ($downtime->is_flexible): ?>
            <?php if ($downtime->is_in_effect): ?>
              <?= sprintf(
                $this->isService
                  ? $this->translate('This flexible service downtime was started on %s at %s and lasts for %s until %s at %s.')
                  : $this->translate('This flexible host downtime was started on %s at %s and lasts for %s until %s at %s.'),
                $this->formatDate($downtime->start),
                $this->formatTime($downtime->start),
                $this->formatDuration($downtime->duration),
                $this->formatDate($downtime->end),
                $this->formatTime($downtime->end)
              ); ?>
            <?php else: ?>
              <?= sprintf(
                $this->isService
                  ? $this->translate('This flexible service downtime has been scheduled to start between %s - %s and to last for %s.')
                  : $this->translate('This flexible host downtime has been scheduled to start between %s - %s and to last for %s.'),
                $this->formatDateTime($downtime->scheduled_start),
                $this->formatDateTime($downtime->scheduled_end),
                $this->formatDuration($downtime->duration)
              ); ?>
            <?php endif ?>
            <?php else: ?>
              <?php if ($downtime->is_in_effect): ?>
                <?= sprintf(
                  $this->isService
                    ? $this->translate('This fixed service downtime was started on %s at %s and expires on %s at %s.')
                    : $this->translate('This fixed host downtime was started on %s at %s and expires on %s at %s.'),
                    $this->formatDate($downtime->start),
                    $this->formatTime($downtime->start),
                    $this->formatDate($downtime->end),
                    $this->formatTime($downtime->end)
                ); ?>
              <?php else: ?>
                <?= sprintf(
                  $this->isService
                    ? $this->translate('This fixed service downtime has been scheduled to start on %s at %s and to end on %s at %s.')
                    : $this->translate('This fixed host downtime has been scheduled to start on %s at %s and to end on %s at %s.'),
                    $this->formatDate($downtime->start),
                    $this->formatTime($downtime->start),
                    $this->formatDate($downtime->end),
                    $this->formatTime($downtime->end)
                ); ?>
              <?php endif ?>
            <?php endif ?>
      </small>
    </td>
  </tr>
</table>