Since WordPress 5.2 there is a built-in feature that detects when a plugin or theme causes a fatal error on your site, and notifies you with this automated email.
In this case, WordPress caught an error with one of your plugins, WP Crontrol.
we been using the plugin for a while with no problems. As soon as updated to 2.8.2 the whole site returns error 500 which goes away when we deactivate the plugin.
Please let us know as the problems is coming from the update.