It used to be the polite thing to disclose that you used a translation app. In fact, traditionally, you disclose when you translate anything so people know the context in which to interpret your text.

In the same way, I wanna know if a book is written by some famous people just ghost written.

Of course, the point is moot. Somebody using AI to write a blog post is unlikely to be self conscious enought to thing it's necessary to disclose it in the first place.