const [checkedBoxesDate, setCheckedBoxesDate] = useState([]);

// 1. Działa
  const handleCheckBoxDate = (position1, position2) => {
    const chkBoxesCopy = JSON.parse(JSON.stringify(checkedBoxesDate)); // deep copy
    chkBoxesCopy[position1][position2] = !chkBoxesCopy[position1][position2];
    setCheckedBoxesDate(chkBoxesCopy);
  }

  // 2. Nie działa ?
  const handleCheckBoxDate = (position1, position2) => {
    setCheckedBoxesDate((chkBoxes)=>{
      chkBoxes[position1][position2] = !chkBoxes[position1][position2];
      return chkBoxes;
    })
  }