create shortcode to list users with specific meta key value

Try this:

function thebroker_agents() {
    global $current_user;
    $bmail = $current_user->user_email;
    $user_query = new WP_User_Query( array( 'meta_key' => 'broker_email', 'meta_value' => $bmail,  'fields' => 'all'  ) );
    $users = $user_query->get_results();
    if (!empty($users)) {
        $results="<ul>";
        foreach ($users as $user){
            $results="<li>" . $user->display_name . '</li>';
        }
        $results="</ul>";
    } else {
        $results="No users found";
    }
    wp_reset_postdata();
    return $results;
}
// Adds the above function as as shortcode
add_shortcode( 'your_agents', 'thebroker_agents' );

You were missing a last bracket. Also I changed the code a bit from echoing, to returning your results. I also reset your post data. Not sure why you didn’t use a while statement in your code, but left that alone.

Since you are calling your function in php, you don’t need a short code. you can call it just like this:

echo thebroker_agents();

However your echo do shortcode will still work as well.