Filter Profile Builder username and add extra text after it for information purposes.

gistfile1.php

// filter Profile Builder username and add extra text after it for information purposes. 
add_filter('wppb_register', 'pb_edit_registration_username', 10, 1);
function pb_edit_registration_username($registerFilterArray2){ 
  $registerFilterArray2['name2']  .= 'text here'; 
	return $registerFilterArray2; //returns the default (formatted) input + your custom text
}