The User Statistics report is based on the user summary sys schema views. For more information, see The user_summary and x$user_summary Views.
This graph is displayed only if a MySQL instance is selected in the All Targets drop-down menu.
The table view lists the statistics in a standard table format. The data can be sorted by column.
Existing users who have never logged on to the instance are not listed in the results.
mysql.sysuser is not listed in the results.
backgrounduser is the owner of the background threads running on the instance. Such as the storage engine threads, main server thread, and event scheduler.