How to work with flatpickr in symfony?

Question

symfony

I connect flatpickrto fields with a classdatetime-input

flatpickr('.datetime-input', {
    defaultDate: "today",
    minDate: "today",
    dateFormat: "Y-m-d H:i:s",
    time_24hr: true,
    enableTime: true
});

I do the field datetimetypeas I single_text

save it to the database, everything works perfectly,
but if I display the saved record for editing, the saved date is not picked up and the default date is displayed.
moreover, if you remove widget='single_text', the date in separate inputs is displayed correctly