AWS role vs iam credential in duckdb HTTPFS call

I am pretty baffled and I don’t know what is going on with this one.

I’m using DuckDB to query parquet files in an s3 bucket.

import pandas as pd
import duckdb

query = """
    INSTALL httpfs;
    LOAD httpfs;
    SET s3_region='us-west-2';
    SET s3_access_key_id='key';
    SET s3_secret_access_key='secret';
    SELECT 
        FROM read_parquet('s3://bucket/folder/file.parquet') 

cursor = duckdb.connect()

cursor.execute(query).df()

I have an IAM user with admin access. I am able to query this parquet file with programatic access keys. I also have a role that I want to use in an application that I have also given admin access just for testing purposes.

When I assume the role and create temporary credentials and input those into the code above

export $(printf "AWS_ACCESS_KEY_ID=%s AWS_SECRET_ACCESS_KEY=%s AWS_SESSION_TOKEN=%s" 
$(aws sts assume-role 
--role-arn arn:aws:iam::<account-id>:role/<role-name> 
--role-session-name test-session 
--query "Credentials.[AccessKeyId,SecretAccessKey,SessionToken]" 
--output text))

I get the error

duckdb.Error: Invalid Error: Unable to connect to URL
"s3://bucket/folder/file.parquet": 403 (Forbidden)

However, when I use my IAM user, I am able to access this s3 object and query the data just fine. Is there something I am missing about the difference between roles and IAM users?

If it helps, what I am trying to do is create a role for a lambda function and then access the environmental variables AWS_ACCESS_KEY_ID, and AWS_SECRET_ACCESS_KEY with os.getenviron() in the code above. I believe if I can get the role working by writing in the temporary credentials it should work when I use os.getenv() in the lambda function.