Why is a self-closing iframe tag preventing further DOM elements to be displayed?

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On Firefox and Safari, the following code displays only the first iframe

<iframe src=\"http://www.tsr.ch\"/&gt         
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                <span>2020-11-28 16:49</span>
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<p>There's no such thing as a "self-closing iframe" in HTML (or, for that matter, any other kind of self-closing tag, there are just some elements where the end tag can or must be omitted and iframe is not one of them).</p>

<p>You have an iframe <strong>start tag</strong> with an invalid <code>/</code> at the end of it.</p>

<p>Everything that follows is a child node of the iframe, so it treated as alternative content for browsers that don't support iframes.</p>

<hr>

<p>XHTML supports self-closing tags, and any element may be added using one (if you aren't being HTML compatible).</p>

<p>HTML 5 allows for a <code>/</code> at the end of a start tag for an element when the end tag is omitted, but it has no effect beyond satisfying XML addiction and bad syntax highlighters.</p>
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                <span>2020-11-28 17:08</span>
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<p>Because the <code>iframe</code> element <strong>isn't</strong> a self-closing element. The versions of Firefox and Safari you're using are treating the <code>/&gt;</code> at the end as just <code>&gt;</code> and assuming everything after it is contained within the <code>iframe</code>.</p>
<p>If we attempt to pass the code you've given through W3C's validator we'll see the following errors:</p>
<blockquote>
<p>Error: Self-closing syntax (<code>/&gt;</code>) used on a non-void HTML element. Ignoring the slash and treating as a start tag.</p>
<pre><code>&lt;iframe src=&quot;http://www.bing.com&quot;/&gt;
</code></pre>
<p>Error: End of file seen when expecting text or an end tag.</p>
<pre><code>&lt;/html&gt;
</code></pre>
<p>Error: Unclosed element <code>iframe</code>.</p>
<pre><code>&lt;iframe src=&quot;http://www.bing.com&quot;/&gt;
</code></pre>
</blockquote>
<p>If you inspect your document with your browser's Element Inspector, you'll see what's going on.</p>
<p>Chrome, which I'm using, converts the invalid <code>&lt;iframe ... /&gt;</code> to <code>&lt;iframe ...&gt;&lt;/iframe&gt;</code>:</p>
<p><img src="https://i.stack.imgur.com/tndTq.png" alt="Chrome Example" /></p>
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