Paste this into a Klaviyo HTML block (change the host + deadline):

<img src="https://YOUR-HOST/countdown.gif?until=2026-09-15T09:00:00Z&t={% today '%s' as t %}{{ t }}" width="581" height="137" alt="Drop launching in" border="0" style="display:block;width:100%;max-width:581px;height:auto;" />

Preview (set ?until= on /countdown.gif):