Line Breaks in Email Checkboxes

I am trying to use this hook to separate my checkboxes by line vs a comma. But when I use it my checkbox values don’t appear in my recieved email. I am not sure what I am doing wrong.

add_filter( 'wpcf7_mail_tag_replaced',
 
  function( $replaced, $submitted, $html, $mail_tag ) {
    if ( 'checkbox_name' == $mail_tag->field_name() ) {
      $replaced = str_replace(",", "<br>", $submitted );
    }
 
    return $replaced;
  },
 
  10, 4
);'