First H2 Appears Error \"text-align center

First H2 in every post like that http://prntscr.com/hhwn3a

this is making a problem for me when I try to validate AMP for posts https://search.google.com/test/amp?utm_source=gws&utm_medium=onebox&utm_campaign=suit&id=Ou9hng3FEGsKgFMMytUGhw

The post url : https://www.decorationy.com/interior-design/outdoor/best-stone-patio-ideas/

Yes, you need to remove all inline HTML to pass AMP validation.

Best way is to search/replace the dbase using MySQL/phpMyAdmin or similar (see various tutorials online on how to do this). Not part of theme. The center text element in posts is part of WordPress editor, and technically should always have been a style ‘class.’

Basically you need to change anything that you want centered to a
class="text-center"

Same with any inline styles you may have used for tables or comparable.

Hope that helped!