DataTable and ajax json

HTML

<script src="https://cdn.datatables.net/1.10.20/js/jquery.dataTables.min.js"></script>
<link rel="stylesheet" href="https://cdn.datatables.net/1.10.20/css/jquery.dataTables.min.css">
    
     <table id="example" class="display">
      <thead>
            <tr>
                <th colspan="3">Lab101 Lab Info</th>
                <th colspan="5">ComboMatch Info</th>
            </tr>
             <tr>
                 <th>Lab101 Lab Id</th>
                 <th>specimen<br/>collection date</th>
                 <th>specimen<br/>sequencing date</th>
                 <th>study Id</th>
                 <th>Scenario Id</th>
                 <th>Prior Registration</th>
                 <th>Current Treatment Assignment(s)</th>
		 <th>Expand for Details</th>
             </tr>
      </thead>
    </table>

CSS

body {
  font: 90% 1.45em "Helvetica Neue", HelveticaNeue, Verdana, Arial, Helvetica, sans-serif;
  margin: 0;
  padding: 0;
  color: #333;
  background-color: #fff;
}

td.details-control2{
    background: url('https://www.datatables.net/examples/resources/details_open.png') no-repeat center center;
    cursor: pointer;
}
tr.shown td.details-control{
    background: url('https://www.datatables.net/examples/resources/details_close.png') no-repeat center center;
}

div.reason {
  width: 100%;
  overflow: hidden;
  white-space: normal;
}

JavaScript

var json = [
{
  "lab_id": "LAB101",
  "study_id": "NCT101",
  "is_registered": false,
  "lab_scenario_id": "SAMPLE01",
  "specimen_collection_date": "2023-04-13T00:00:00+00:00",
  "specimen_sequencing_date": "2023-04-13T00:00:00+00:00",
  "sample_type": "SOMATIC",
  "variants": [
    {
      "genomic_build": "GRCh37",
      "allele_frequency": 0.45,
      "chromosome": "10",
      "position": "90773893",
      "ref": "T",
      "alt": "C",
      "output_genomic_build": "GRCh37",
      "submission_type": "DISCRETE_VAR_VIA_VARIANT_TYPE",
      "type": "SNV",
      "normalized_data": {
        "identifiers": {
          "COSMIC": [],
          "CLINVAR": [
            "VCV000877928"
          ],
          "CLINGEN": [
            "CA5593210"
          ]
        },
        "genomic": {
          "genomic_var_type": "snv",
          "genomic_hgvs": "NC_000010.10:g.90773893T>C",
          "genomic_acc_ver": "NC_000010.10",
          "genomic_position": 90773893,
          "genomic_chr": "10",
          "genomic_ref": "T",
          "genomic_alt": "C",
          "output_genomic_build": "GRCh37",
          "molecular_consequence": [
            "inframe",
            "missense"
          ]
        },
        "transcript": [
          {
            "transcript_hgvs": "NM_000043.4:c.694T>C",
            "transcript_acc_ver": "NM_000043.4",
            "transcript_change": "c.694T>C",
            "protein": {
              "protein_hgvs": "NP_000034.1:p.Tyr232His",
              "protein_acc_ver": "NP_000034.1",
              "protein_change": "p.Tyr232His",
              "protein_1letter_change": "p.Y232H",
              "oncomine_protein": "p.Tyr232His"
            }
          }
        ],
        "allele_frequency": 0.45,
        "gene": {
          "gene_id": 355,
          "gene_symbol": "FAS",
          "gene_name": "Fas cell surface death receptor",
          "gene_aliases": [
            "ALPS1A",
            "APO-1",
            "APT1",
            "CD95",
       ...