PostgreSQL Node incorrectly adds "Z" suffix to TIMESTAMP WITHOUT TIME ZONE values

[bene]

Describe the problem/error/question

The PostgreSQL node in n8n incorrectly appends “Z” (UTC indicator) to timestamp values retrieved from columns defined as TIMESTAMP WITHOUT TIME ZONE. This causes downstream nodes (especially LLMs) to misinterpret local timestamps as UTC values, leading to incorrect timezone conversions.

Inputs in Postgres Node to test (need a running Postgres db)

Share the output returned by the last node

Here is what´s being returned:

[
  {
    "id": 1,
    "test_column": "2025-10-18T13:00:00.000Z",
    "description": "exactly 13:00 local time"
  },
  {
    "column_name": "test_column",
    "data_type": "timestamp without time zone",
    "is_nullable": "YES"
  }
]

Information on your n8n setup

• n8n version: [email protected]
• Database (default: SQLite): Postgresql
• n8n EXECUTIONS_PROCESS setting (default: own, main): own
• Running n8n via (Docker, npm, n8n cloud, desktop app): cloud
• Operating system: mac