select results on pg_class incomplete

Hi

I am trying to access PostgreSQL meta data, possibly in a vane attempt 
to get size data.

I use DbVis with a connection as shown in https://ibb.co/2SDzhXt . I try 
to get information on a regular table "umsaetze". When doing the DbVis 
object I can see them - https://ibb.co/WxMnY2c . If I execute following 
SQL query in DbVis's SQL Commander, the result set is empty - 
https://ibb.co/GngdWLH .

select *
   from PG_CLASS
  where RELNAME = 'umsaetze';

I noticed that the sessions producing the different results are not the 
same - https://ibb.co/wdKcCFc , but seem to connect to different 
databases. The "missing" table is indeed in the budget database.

The connection user is, apart from being member of pg_monitor vanilla - 
https://ibb.co/DGs6sQz and https://ibb.co/8xzHrvP .

It seems, that in pg_class only is, with respect to custom databases, 
listed what is in the database one connects to - https://ibb.co/dbbJVbJ.

template1=> select count(*)
   from PG_CLASS
  where RELNAME = 'umsaetze';
  count
-------
      0
(1 row)

template1=> \q

C:\Users\thiemo\AppData\Roaming\MOBAXT~1\home>psql -h hp-slimline-260 -p 
5436 -U monitor budget
psql (11.2, server 16.1 (Debian 16.1-1.pgdg110+1))
WARNING: psql major version 11, server major version 16.
          Some psql features might not work.
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384, 
bits: 256, compression: off)
Type "help" for help.

budget=> select count(*)
   from PG_CLASS
  where RELNAME = 'umsaetze';
  count
-------
      2
(1 row)

budget=> \q


Is there a possibility to make the user monitor see all the objects of 
the cluster? Background is that I was hoping to create a query to spit 
out the size of tables in the cluster.

Kind regards

Thiemo