Countdown timer doesn't work correctly according to the WP timezone settings. So the sales will end before or after the set date for several hours depending on your timezone configuration. It will only work if you use UTC +0 which was not the case for us. Most of the plugin developers I've dealt with were kind and quick to fix the bugs when I report to them. Even those big names such as Weglot or Algolia who have customers like Microsoft, Stripe, etc. were super quick to fix their bugs that I reported to them. This plugin's author got very offended when I kept mentioning this bug that has been around for years.