Information
A TRIGGER may be used to modify DML actions or invoke other (recursive) actions when some types of user-initiated actions occur. Enabling this audit option will cause auditing of any attempt, successful or not, to create, drop, enable or disable any schema trigger in any schema regardless of privilege or lack thereof. For enabling and disabling a trigger, it covers both ALTER TRIGGER and ALTER TABLE
Triggers are often part of schema security, data validation and other critical constraints upon actions and data. A trigger in another schema may be used to escalate privileges, redirect operations, transform data and perform other sorts of perhaps undesired actions. Any unauthorized attempt to create, drop or alter a trigger in another schema may be cause for 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 TRIGGER;