You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Li_et_al_2023_2.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="199" ns="6" title="File:Bth ozone adjoint.jpeg" />
      <page pageid="21" ns="6" title="File:Curiesmall.PNG" />
      <page pageid="45" ns="6" title="File:DSC02787 1.jpg" />
      <page pageid="135" ns="6" title="File:Enso impacts.png" />
      <page pageid="209" ns="6" title="File:Feng et al 2023 ship COVID.jpeg" />
      <page pageid="201" ns="6" title="File:Group202207.jpg" />
      <page pageid="153" ns="6" title="File:Group outing 202108.jpg" />
      <page pageid="39" ns="6" title="File:Jy01.png" />
      <page pageid="198" ns="6" title="File:Levoglucosan.jpg" />
      <page pageid="215" ns="6" title="File:Li et al 2023.png" />
    </pages>
  </query>
</api>