Cloudflare is blocking your server from accessing the site and instead of returning the feed, it's returning a captcha challenge!
That's the response which was returned instead of the feed:
<!DOCTYPE html>
<html lang="en-US">
<head>
<title>Just a moment...</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=Edge">
<meta name="robots" content="noindex,nofollow">
<meta name="viewport" content="width=device-width,initial-scale=1">
<link href="/cdn-cgi/styles/challenges.css" rel="stylesheet">
</head>
<body class="no-js">
<div class="main-wrapper" role="main">
<div class="main-content">
<h1 class="zone-name-title h1">
<img class="heading-favicon" src="/favicon.ico"
onerror="this.onerror=null;this.parentNode.removeChild(this)">
..
</h1>
<h2 class="h2" id="challenge-running">
Checking if the site connection is secure
</h2>
<noscript>
<div id="challenge-error-title">
<div class="h2">
<span class="icon-wrapper"> <div class="heading-icon warning-icon"></div>
</span>
<span id="challenge-error-text">
Enable JavaScript and cookies to continue
</span>
</div>
</div>
</noscript>
<div id="trk_jschal_js" style="display:none;background-image:url('/cdn-c
...