Airflow job is started before scheduled time

I am confused by the behavior of Airflow scheduling. I have a daily job which should run at 11:59 CET. My understanding is that the job should be run at the end of the data interval which would be Dec 31st 11:59. But instead the job is run on Dec 31st 11:53.

Below is the DAG code. I am using Airflow 2.2.0.

default_args = {
    'owner': 'airflow',
    'start_date': dt.datetime(2018, 9, 24, 10, 00, 00,
    'concurrency': 0,
    'retries': 0,
    'catchup': False,

with DAG('and_another_dag5',
         schedule_interval="59 11 * * *",
         ) as dag:
    dummy = DummyOperator(task_id='run_ths')

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