Tablespace dashboard ignores postgres db and takes other databases

I am trying to use the dashboard designed for finding the tablesize using query:

this dashboard skips/ignores ‘postgres’ db, but if the database name is some other like dev-xxxx or database-A it is populating the details. Could you please advise how to make this include postgres db.

Most of my applications runs on default database (postgres) hence I want to include the metrics of tablespace of postgres db