Use of CSS classes in editor-blocks.css file

Searching the editor source code: https://github.com/WordPress/gutenberg does not show much results. I suggest search the theme source code these classes to see where they are applied. (If you press . while viewing the code on github you will get a VSCode editor)

register_block_type is used to add the block date in WordPress. Typically with these arguments:

 register_block_type( 'custom-plugin/custom-block', array(
        'editor_script' => 'editor-script.js',
        'editor_style'  => 'editor-style.css',
        'style'         => 'frontend.css',
    ) );

editor_script and editor_style add files to editor admin. style is meant to add CSS to frontend.

What documentation does not mention is that style is also loaded in backend. So it is possible those theme are using one file for bother backend and frontend to minimize the code they write.