pre_user_query
is called after the query variable object is created, but before the actual query is run. Your code is creating a new query within the action when you should actually modify the existing query’s arguments using the $query->set()
method. For example:
function my_pre_user_search($user_query) {
$meta_query = array(array(
'key' => 'member_id',
'value' => '2349'
));
$user_query->set('meta_query', $meta_query);
}
add_action('pre_user_query','my_pre_user_search');