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>
    <pages>
      <page pageid="703" ns="0" title="Getting started" />
      <page pageid="740" ns="0" title="Legal Team/Decisions/Dealing with Public Domain within SPDX Files (DRAFT)" />
      <page pageid="741" ns="0" title="Legal Team/License List/Inclusion Guidelines (Background)" />
      <page pageid="742" ns="0" title="Legal Team/License List/Current Issues and Licenses Under Consideration" />
      <page pageid="1182" ns="0" title="Legal Team/Decisions/license expression syntax" />
      <page pageid="1210" ns="0" title="Legal Team/Minutes/2019-0110" />
    </pages>
  </query>
</api>