Information
Enabling the audit option for the SYSTEM GRANT object causes auditing of any attempt, successful or not, to grant or revoke any system privilege or role, regardless of privilege held by the user attempting the operation.
Logging of all grant and revokes (roles and system privileges) can provide forensic evidence about a pattern of suspect/unauthorized activities. Any unauthorized attempt may be cause for further investigation.
Solution
To remediate this setting, execute the following SQL statement in either the non multi-tenant or container database, it does NOT need run in the pluggable.
AUDIT SYSTEM GRANT;