Secondary information in mushroom card

I’m trying to show secondary information using the ‘secondary’ statement referring to the sensor information (remaining climatisation time). But it keeps showing ‘1 hour ago (1 uur geleden in Dutch)’, instead of the remaining time. Hopefully you can advise me:

      - type: custom:mushroom-entity-card
        entity: button.cupra_born_start_climate
        secondary: sensor.cupra_born_remaining_climatisation_time
        fill_container: true
        icon: mdi:leaf-circle-outline
        icon_color: green
          action: toggle