Because in trigger where table fpbackup.fp_vpn_data_2021w12 has
been created there are several DDL commands:
EXECUTE 'CREATE TABLE "' || fp_schema_name || '"."' || fp_table_name || '" (LIKE '|| fp_parent_table_name || '
INCLUDINGDEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES) WITHOUT OIDS TABLESPACE ' || fp_tablespace;
EXECUTE 'ALTER TABLE "' || fp_schema_name || '"."' || fp_table_name || '" OWNER TO fpbkwriter';
The trigger was called by user "worker" that already had permission on
USAGE of schema dict, so table creation was successful. But after that
the ownership of the table was moving to "fpbkwriter" that had no permission on
USAGE of schema dict, thus the error occured.
In reality, there was no user "fpbkwriter" at the beginning. Only user
"worker" was created. And when the user "fpbkwriter" was created, he was
not granted by enough privileges mistakenly.