Invalid date on ios 13.5

im using the calendar for a while. and now on last IOS update (13.5), I get an invalid date on the format value. this is the image when i debug the iphone:
it worked before (return a date), it works on android, and on pc.
i have tried different date format and i get the same error

    var BdCalendar = valueCard.calendar.create({
      inputEl: '.BirthDay-org',
      locale: 'he-IL',
      firstDay: 0,
      closeOnSelect: true,
      dateFormat: 'dd/mm/yyyy',
      formatValue: function (val) {
 var selectedDate = val.toLocaleString("en-IL", { year: 'numeric', month: '2-digit', day: '2-igit' }).split(",")[0];
          return selectedDate;

Do a console.log(val) inside formatValue handler to see what is here