Why are certain tags clipped?

Question

Joomla

There is HTML code in the admin panel:

<p><a href="tel:[phone]"><span style="font-size: 12.16px; line-height: 1.3em;">[phone]</span></a></p>

Call:

<div class='phone'>
                <jdoc:include type="modules" name="contactphone" />
              </div>

Why are links and paragraphs cut off?
Editor: html source editor
Joomla: 2.5.4

Answer 1

1. Update Joomla. Your site is about 11-12 years old. There are plenty of holes that have been fixed during this time. At the moment, 3.10.3 and 4.0.3 are relevant. Update at least three.
2. On the merits of the question - see the editor settings. Usually there are allowed and prohibited tags.

Answer 2

Do not even try to upgrade, as some recommend here. There is a high probability that the site will fail altogether after upgrading to 3 or 4 joomla.
Paragraphs may be cut off due to the built-in editor in modules. When saved, they keep the tags as they are.
but when loading the text editor in an article or in a module, the tags are cleared of prohibited ones. As a rule, in modern Joomla, cleaning comes from scripts and from frames.
Try switching the default tag editor to Codemirror or just a text field, and then check if the tags are clipped or not.
And judging by the fact that your Joomla is old, start thinking quietly to buy a new site on this CMS Joomla version 4, with new requirements, for a mobile phone, for the half-blind, for visibility on smartphone screens on a sunny street day.
If you ask me anything, I can help with a new site.