Backspace key is not working on select2 search filed

Question

It sounds basic, but I am stuck with select2 input search, the search works perfectly but backspace key doesn't, I don't want multi select. Below is my code

function projID(id, tdDate, empKey){debugger;
$("#"+id).select2({
    minimumInputLength: 3,
    placeholder: "Put some text...",
    allowClear : true,
    //tags: true,
    selectOnClose: true,
    initSelection: function(element, callback) {   debugger;
    },
    ajax: {
        url:'getProjectsForTimecardException.action?empKey='+empKey+'&tdDate='+tdDate+'&auditLogsKeyword=' + menuData.globKeyword,
        contentType: 'application/json',
        dataType: 'json',
        data: function(params) {
          return {
            q: params.term, // search term
            page: params.page
          };
        },
        processResults: function (data) {
            $("#"+id).empty().trigger('change');
            return {
                results: $.map(data, function (item) {debugger;
                    return {
                        text: item.value,
                        id: item.key
                    }
                })
            };
        },
        cache: false
      },
      //templateResult: formatResult
    });

}

I am using the verion 4.1.0-rc.0.

Thanks in Advance.

I tried all the possible things available but still no luck

$(document).ready(function() {
    $('#activityId').select2({placeholder: "Put some text...",
        allowClear : true});
      });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
    <link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/select2.min.css" rel="stylesheet" />
    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/select2.min.js"></script>

    <select style="width: 100% !important; border: 1px solid #0B3A42; box-shadow: 0px 0px 3px #ccc, 0 10px 15px #eee inset; height: 35px;border-radius: 5px 5px 5px 5px;" id="activityId">
                             <option>--Hii --</option></select>