Why is meta-command execution being blocked on AWS RDS PostgreSQL ?

The blocking of specific meta-commands like \copy, \i, and \lo_export is likely a security and safety measure. By restricting these commands, the PostgreSQL maintainers (or AWS, if this is an AWS-specific patch) aim to prevent potentially unsafe operations that could be exploited to perform unauthorized actions within the database, especially in a managed environment like Amazon RDS where security and stability are paramount.

If AWS RDS's release notes do not provide sufficient explanation for this change, consider reaching out to AWS Support for more detailed information. Additionally, keeping an eye on PostgreSQL official documentation or mailing lists can provide insights into changes that come with each release, especially for security-related adjustments.