Thank you for reaching out to us, I would check your CSS budget because the AMP framework only allows 75 KB CSS on each page, so the AMP plugin adds CSS optimizations, which are sometimes exceeded by third-party plugins or themes.
If you are not sure how to find exceeding CSS budget, follow the below steps:
1) Make sure you have enabled the AMP validation tool
Go-to: Users > Profile > check the checkbox for AMP Development tool > save
2) Visit AMP page exceeding CSS budget check Admin bar for AMP option locate submenu CSS budget and click on it (screenshot)
3) Locate the source of excessive CSS (screenshot)
4) If one of the plugins adds excessive CSS find an alternative plugin from the AMP ecosystem
You can learn more about the Reader mode video below:
