remove previous code and add following code in your theme’s (child theme’s if any) functions.php
add_filter( 'fep_filter_user_name', function( $name, $id ){
if( function_exists( 'um_fetch_user' ) ){
um_fetch_user( $id );
$name = '<a href="' . um_user_profile_url() . '">' . $name . '</a>';
}
return $name;
}, 10, 2);