Why posts_per_page doesnt work? (wordpress)

Question

I'm attempting to avoid querying all of my site's posts, as there are many and the site becomes slow when this script runs.

I've read every similar question and done the following without success:

• using showposts parameter
• adding wp_reset_query();
• passing args as an array

but nothing seems to work, it always returns all the posts.

$the_query = new WP_Query( 'posts_per_page=8' );

$blogs = [];

    while ($the_query -> have_posts()): $the_query -> the_post();
        $post_categories = [];
        foreach (get_the_category($post->ID) as $key => $cat) {
            if($cat->term_id == 2) continue;

            array_push($post_categories,
                "<a href='". get_category_link($cat->term_id) ."'>{$cat->name}</a>"
            );
        }

        $blogs[] = [
            'title' => get_the_title($post->ID),
            'abstract' => substr(wp_strip_all_tags($post->post_content), 0, 80)
        ];
    endwhile;

}