I got it to work! It seems like we need to set

s3 -> s3a

and handle auth in a special way spark-on-k8s-operator/issues/1041. The following code worked.

def configure_s3(spark):
    hadoop_conf = spark._jsc.hadoopConfiguration()
    hadoop_conf.set("fs.s3.impl", "org.apache.hadoop.fs.s3a.S3AFileSystem")
    hadoop_conf.set("fs.s3a.aws.credentials.provider", "com.amazonaws.auth.WebIdentityTokenCredentialsProvider")


@task(container_image="<http://ghcr.io/flyteorg/flytecookbook:k8s_spark-latest|ghcr.io/flyteorg/flytecookbook:k8s_spark-latest>", task_config=Spark(
        spark_conf={
            "spark.driver.memory": "1000M",
            "spark.executor.memory": "1000M",
            "spark.executor.instances": "3",
            "spark.driver.cores": "1",
            "spark.executor.cores": "1",
        }),
)
def t1() -> StructuredDataset:
    spark = flytekit.current_context().spark_session
    configure_s3(spark)

    df = pd.DataFrame({"a": [1,2,3]})
    df = spark.createDataFrame(df)
    return StructuredDataset(dataframe=df)

I just made an issue https://github.com/flyteorg/flyte/issues/3630