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>
    <allpages gapcontinue="Test" />
  </query-continue>
  <query>
    <pages>
      <page pageid="4830" ns="0" title="Sheets">
        <revisions>
          <rev contentformat="text/x-wiki" contentmodel="wikitext" xml:space="preserve">=='''Test page google sheets'''==
&lt;html&gt;
&lt;iframe referrerpolicy=&quot;no-referrer&quot; src=&quot;https://docs.google.com/presentation/d/e/2PACX-1vTNMKq495C8g5c5WNJTuVMchSst17YBpxQMZp-LQD8bJmTA1MNZoN1Fu2rQHQ2J9PkbEqVPfcz0Nlnw/embed&quot; webkitallowfullscreen=&quot;true&quot;&gt;&lt;/iframe&gt;
&lt;/html&gt;

&lt;p&gt;Here&amp;#8217;s an example of an embedded Google Slides presentation.&lt;/p&gt;
&lt;html&gt;
&lt;iframe loading=&quot;lazy&quot; src=&quot;https://docs.google.com/presentation/d/e/2PACX-1vQOsQmTwa7JW3GP5yDieSTDMBBB4hiNO0YCIX6gOpbjHaifex2ASzV22_F9cmdW4VpnP9TpLIG-Ehro/embed?start=false&amp;amp;loop=false&amp;amp;delayms=3000&quot; width=&quot;768&quot; height=&quot;455&quot; frameborder=&quot;0&quot; allowfullscreen=&quot;allowfullscreen&quot;&gt;&lt;/iframe&gt;
&lt;p&gt;This &lt;a href=&quot;https://youtu.be/Ye3bLjstvpg&quot; target=&quot;_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;3 minute video&lt;/a&gt; takes you through the process described above.&lt;/p&gt;
&lt;figure&gt;&lt;iframe loading=&quot;lazy&quot; src=&quot;https://www.youtube.com/embed/Ye3bLjstvpg&quot; width=&quot;767&quot; height=&quot;432&quot; frameborder=&quot;0&quot; allowfullscreen=&quot;allowfullscreen&quot;&gt;&lt;/iframe&gt;
&lt;/html&gt;</rev>
        </revisions>
      </page>
      <page pageid="4831" ns="0" title="Sheets2">
        <revisions>
          <rev contentformat="text/x-wiki" contentmodel="wikitext" xml:space="preserve">
Sheet2

&lt;html&gt;
&lt;iframe src=&quot;https://docs.google.com/document/d/e/2PACX-1vRuWdytr8_J8ru5Y3vKam-UrB48d9q15bLkTuPkyc0zHEhelcoh4WZIcN9_VB1cIKQROROtfpPJLArm/pub?embedded=true&quot;&gt;&lt;/iframe&gt;
&lt;/html&gt;</rev>
        </revisions>
      </page>
    </pages>
  </query>
</api>