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 apcontinue="Fehler_in_E-Mail-Warteschlange_beheben" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="73" ns="0" title="Bootstrap Spaltenset-Elemente ohne Erweiterung &quot;Bootstrap für Contao&quot; nutzen" />
      <p pageid="15" ns="0" title="CSV Datei" />
      <p pageid="65" ns="0" title="Composer Update über SSH" />
      <p pageid="58" ns="0" title="Contao 4 lokal installieren (Win10/XAMPP)" />
      <p pageid="34" ns="0" title="Contao Theme erstellen" />
      <p pageid="52" ns="0" title="Dk mmenu" />
      <p pageid="43" ns="0" title="Edge Navigationsfix" />
      <p pageid="10" ns="0" title="Erster Buchstabe groß" />
      <p pageid="20" ns="0" title="FAT online Handbuch" />
      <p pageid="66" ns="0" title="Fehler bei E-Mail-Empfängern beheben" />
    </allpages>
  </query>
</api>