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="1" ns="0" title="Main Page">
        <revisions>
          <rev user="MediaWiki default" anon="" timestamp="2015-03-20T05:40:59Z" comment="" />
          <rev user="DevliN" timestamp="2015-03-23T06:19:30Z" comment="" />
          <rev user="DevliN" timestamp="2015-03-23T06:21:22Z" comment="" />
          <rev user="Zurg" timestamp="2015-08-01T02:09:54Z" comment="Sprucing up the front page a bit" />
          <rev user="Jim Raynor&#039;s armored jockstrap" timestamp="2020-04-09T08:02:32Z" comment="correct grammar and link to [[special:allpages]]" />
        </revisions>
      </page>
    </pages>
  </query>
</api>