Duplicate rows on rendered_task_instance_fields

### Apache Airflow version

3.0.3

### If "Other Airflow 2 version" selected, which one?

_No response_

### What happened?

Here is the error on the first try. But on the second try, the task was successful with no error. While I get the error and it is still running/trying the DAG is not shown in the UI anymore. The problem happens randomly on any task of the DAG. The task is Kubernetes POD operator calling a Python module under docker. It's on AKS and the database of Airflow is Postgres.

Task failed with exception: source="task"
AirflowRuntimeError: API_SERVER_ERROR: {'status_code': 409, 'message': 'Server returned error', 'detail': {'detail': {'reason': 'Unique constraint violation', 'statement': 'INSERT INTO rendered_task_instance_fields (dag_id, task_id, run_id, map_index, rendered_fields, k8s_pod_yaml) VALUES (%(dag_id)s, %(task_id)s, %(run_id)s, %(map_index)s, %(rendered_fields)s, %(k8s_pod_yaml)s)', 'orig_error': 'duplicate key value violates unique constraint "rendered_task_instance_fields_pkey"\nDETAIL: Key (dag_id, task_id, run_id, map_index)=(sdds_dag_view_snapshot, task_group3.snapshot_START_sec_bond, manual__2025-07-29T21:54:12.221693+00:00, -1) already exists.\n', 'message': 'Serious error when handling your request. Check logs for more details - you will find it in api server when you look for ID R8X88i8e'}}}

### What you think should happen instead?

It should not get that error. Also the DAG has to keep presenting in the UI since it is parsed correctly.

### How to reproduce

Not sure if anyone can reproduce it since it is random but let me know if more info needed. Thanks

### Operating System

Azure - AKS running container / docker.

### Versions of Apache Airflow Providers

3.0.3 (latest version)

### Deployment

Docker-Compose

### Deployment details

_No response_

### Anything else?

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start by tracing the API server handling of inserts into rendered_task_instance_fields and the Kubernetes pod task's rendering path, using the reported PostgreSQL unique-constraint error as the entry point. Investigate why the same dag_id, task_id, run_id, and map_index can be inserted twice; done means the duplicate failure is prevented and the DAG remains visible in the UI during task execution.

Written by the indexing model from the issue text.