vacuumlo Permission Discrepancy Between Prod and Dev on AWS Aurora PostgreSQL

We have several AWS Aurora PostgreSQL 11.21 clusters. Our goal is to remove large objects (LOBs) stored in the pg_largeobject table. The application code has already been refactored to stop using LOBs.

To test the cleanup process, we cloned the production database and ran vacuumlo. Since the LOBs are associated in a custom way, all of them were treated as orphans and successfully removed — which is exactly what we wanted.

Here’s where it gets tricky: in the development environment, running the same vacuumlo command fails with the following error:

Removing lo 19481964
vacuumlo: error: failed to remove lo 19481964: ERROR: must be owner of large object 19481964
Removal from database "hecosdb" failed at object 0 of 1000.

In both the production and development environments, the LOBs are owned by the same three application users. The user running vacuumlo is not the owner of the LOBs in either environment. Also, there are no superuser privileges available on AWS RDS.

Despite this, vacuumlo works fine in production using the RDS master user, but fails in development with the same user due to permission issues.

As a workaround, we're currently running an ALTER LARGE OBJECT ... OWNER TO username loop to reassign ownership. However, this process is extremely slow, as we can only execute the changes one by one due to resource constraints.

Why does vacuumlo succeed in production but fail in development, even though the setup appears similar?