The comment content comes from this placeholder in the "chunk.comment.inc.html" jot template:
[+comment.content:wordwrap:esc:nl2br+]
That "esc"
phx modifier modifies the content so that all html code is escaped and outputted as string. So if you take that "esc" out from the placeholder modifiers, you can insert what ever html you want to the comment content. But that wouldn’t be very good idea if the comment form is some public form.
It would be better to do an own custom modifier that modifies the output by stripping out some tags, while leaving others untouch. Eg. do a snippet with name "phx:myesc" with this content:
<?php
return strip_tags($output, "<a>");
?>
And replace the "esc" in Jot comment content placeholder with myesc, like so:
[+comment.content:wordwrap:myesc:nl2br+]