Public Database links are used to allow connections between databases. Rationale: Using public database links in the database can allow anyone with a connection to the database to query, update, insert, delete data on a remote database depending on the userid that is part of the link.
Solution
To remediate this setting, execute the following SQL statement, keeping in mind if this is granted in both container and pluggable database, you must connect to both places to revoke. DROP PUBLIC DATABASE LINK <DB_LINK>;