I see now what you mean. That's why I was asking in the comments section on codecanyon if you use any shortcodes or something else to display that content. As I opened up the page editor I noticed that the pages are built with some kind of page builder “Content Composer” I guess.
The problem is that “Content Composer” plugin does NOT store the text in the post database in the description field, but somewhere else. If you switch to the classic editor, you see that the actual post content is empty: https://i.imgur.com/08dyuY0.png
So there is nothing to search for in the database, since the post content is not stored there.
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