Exported posts + images issue

If you’re just moving the site to a new location, please follow this guide: https://wordpress.org/documentation/article/moving-wordpress/

If you’re importing content into another existing site, the export only includes images that have been attached to posts and pages, it will not include media that was specifically uploaded only to the media library or via plugins.

As for in-content references to images, if they were not attached to the post or page they’re in, you’ll need to edit them to point to the new file’s location. If you can identify a pattern to the old URLs vs. new URLs, a plugin like https://wordpress.org/plugins/better-search-replace/ might help with that.

I can guarantee that all images are uploaded via WordPress

To be clear, what I meant is that only media uploaded in the editor when writing or editing a post or page is included in the export.

Media uploaded at Media > Add New in your Dashboard or via a plugin is not included in the export.

I am not moving a site, I am trying to debug why the live database is slow, while I create a new site, the database is fast.

Then, I recommend moving the site by following the steps at https://wordpress.org/documentation/article/moving-wordpress/

Exports only contain post/page/comment content and attached media, they are not a copy of your site and thus not sufficient for debugging.