Allow me some time to build a small example project.
I have tried to log the SQL statements but they all appear OK. As expected, non of the statements contain 'Document' to include the BLOB field (i.e. lazy loading). However, when attempting to execute above code (blob to pdf viewer, so attempting to read the blob), the exception is raised but no sql is logged (i.e. it does not seem to get to the point where it would load the blob content).
This application is built with Interbase 2020. Can the example project be with Interbase (I'll include DML statements) or do you prefer SQLite?