I found out this following 3rd party plugin injected those Javascript and invalid css stylesheet on AMP page.

/public_html/plugins/jsnimageshow/themeclassic/classes/jsn_is_themedisplay.php
/public_html/plugins/system/ampz/ampz.php

I already help you applied some fix in these 2 file, it should work fine now.

thank you Arlex. What is the issue so I can report this to the software supplier.

Hello Abraham,

I believe these plugins shouldn't be generating any script / css tags when the format of the page isn't html. You should notify them about this.

For instance, this is how one would check to ensure that the page is currently a HTML document in Joomla.

[gist]
<?php
if (JFactory::getDocument()->getType() != 'html') {
// Since this is not a html document, shouldn't generate any html tags
return;
}
[/gist]