Add shortcode within the_content()

Here’s what I’ve used after finding something on the web (wpbeginner).
It finds the fourth p tag closing and adds it after that. Originally it was to add ad banners in the middle of post content dynamically.

add_filter( 'the_content', 'prefix_insert_post_related' );

function prefix_insert_post_related( $content ) {

$related_code .= do_shortcode("[divider]");
$related_code .= do_shortcode("[bws_related_posts]");

if ( is_single() && ! is_admin() ) {
    return prefix_insert_after_paragraph( $related_code, 4, $content );
}

return $content;
}

function prefix_insert_after_paragraph( $insertion, $paragraph_id, $content ) {
$closing_p = '</p>';
$paragraphs = explode( $closing_p, $content );
foreach ($paragraphs as $index => $paragraph) {

    if ( trim( $paragraph ) ) {
        $paragraphs[$index] .= $closing_p;
    }

    if ( $paragraph_id == $index + 1 ) {
        $paragraphs[$index] .= $insertion;
    }
}

return implode( '', $paragraphs );
}