wp_shortpixel_critical_css_api_cron is late to run

If you get a message on your Site Health screen that says something like this,

The scheduled event, wp_shortpixel_critical_css_api_cron, is late to run. Your site still works, but this may indicate that scheduling posts or automated updates may not work as intended.

this means that your website is having problems running your cron jobs. Cron jobs are scheduled tasks that run at some point in the future, and WordPress has its own cron utility called WP-Cron.

There are a few explanations as to why you received this message:

• Since WP-Cron is only triggered on page load, if you have very low traffic, cron jobs might not start at the scheduled time. If this is the case, you might want to replace WP-Cron with a server cron.
• If you have disabled WP-Cron to replace it with a server cron (you should never disable WP-Cron and not replace it with a server cron), there may be an issue with the server cron. Please ask your hosting provider if everything is all right.