BSOD with PG Database and scram/md5 authentication - old pglib

In the meantime I am on D 9.5.2 with my test site. I am also testing functions related to the External Entities module with PostgreSQL access, so some database related modules are now activated (no more plain Drupal site).

With that said, there is no more WSOD when enabling VDC and I can also configure a VDC view without WSOD. I would assume that there are some dependencies to PostgreSQL modules which are not explicitely stated in the dependency tree.

However I am getting an error message while running the underlying PostgreSQL query:

SQLSTATE[42P01]: Undefined table: 7 ERROR: relation "provider" does not exist LINE 3: "provider" "provider" ^: SELECT "provider"."provider_id" AS "provider_id", "provider"."provider_identifier" AS "provider_provider_identifier", "provider"."provider_name" AS "provider_provider_name", "provider"."provider_name_suffix" AS "provider_provider_name_suffix" FROM "provider" "provider" LIMIT 11 OFFSET 0; Array ( )

The structure of the referenced PostgreSQL table is listed below:

        Column        |          Type          | Collation | Nullable |                    Default                    
----------------------+------------------------+-----------+----------+-----------------------------------------------
 provider_id          | integer                |           | not null | nextval('provider_provider_id_seq'::regclass)
 provider_name        | character varying(100) |           | not null | 
 provider_identifier  | bigint                 |           | not null | 
 provider_type        | integer                |           |          | 
 provider_description | text                   |           |          | 
 provider_name_suffix | character varying(100) |           |          | 
 provider_postalcode  | integer                |           |          | 
 provider_city        | character varying(100) |           |          | 
 provider_active      | boolean                |           | not null | 
Indexes:
    "provider_pk" PRIMARY KEY, btree (provider_id)

The configuration of the additional PostgreSQL database in settings.php is listed below:

$databases['plan_e']['default'] = array (
  'database' => 'plan_e',
  'username' => 'plan_e_ro',
  'password' => '*****',
  'prefix' => '',
  'host' => '*****',
  'port' => '5432',
  'namespace' => 'Drupal\\Core\\Database\\Driver\\pgsql',
  'driver' => 'pgsql',
);

Please note that the table is in the schema plan_e (not public).