Creating query to show which editor (classic or block) was last used to edit a post/page

Can you not just go by date? Assuming you made a clean switch from classic to Gutenberg?

Otherwise, there’s no definitive meta value, but you could just check the post content for common Gutenberg comments, such as <!-- wp:paragraph -->.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)