Site taken down by cleantalk – wp_doing_cron issue

We have a site that has been using cleantalk for quite sometime. The site is on WP 4.5. Apparently on November 24th something happened where suddenly the plugin was looking for a wp_doing_cron function that wasn’t even introduced until WP 4.8. The website was presenting a 500 error until today when we noticed. We ripped the cleantalk plugin out and now the site is up.

With Cleantalk being compatible with WP 3.0 and higher, why did this happen? A website was down for over a week because of this!