Cannot change textColor of background events in fullcalendar

I am using fullcalendar.io v6 in my vue app with normal events and background events. However I want to change the textColor, which works with normal events perfectly but the background events doesn´t change unless I remove display: ‘background’. How can I customize the textcolor of my background events?

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 {
    task_id: 2,
    title: 'Test Time event',
    start: '2024-06-10T15:00:00',
    end: '2024-06-10T16:00:00',
    display: 'background',
    backgroundColor: '#ff9f89',
    borderColor: '#ff9f89', 
    textColor: 'green'
  }