I am using gatsby js to build my static amp page and you can see the final html output in the search console. You can see that the generated html passes amp validation. That test passes because I copy and pasted the generated html.
However the website fails because on page load the official amp script <script async src="https://cdn.ampproject.org/v0.js"></script> adds ineligible tags. If I remove the script, the html stays the same. There are other scripts but I am 99% sure it's ^ one because I tried removing them one by one.
The script adds things like amp-version i-amphtml-sizer in the css and changes other things on the page. I am not sure why it would add these tags because v0.js is recommended by amp.
You can see the failing page here. https://search.google.com/test/amp?id=aClwacaTtbw5q7-Dm3glPg&skip_amp_follow=true
If someone can point me to the original amp v0.js I will be truly grateful. The CDN version is uglified+transpiled and it's really hard to debug my issue.
This was caused by amp cache. I had to follow this guide to invalidate the cache for all my amp pages.