If you just want to write a single <option>
for the current user, you can get the user object from wp_get_current_user() – you don’t need a WP_User_Query at all:
function getŠ”urrentUserForFilter() {
if ( is_user_logged_in() ) {
$user = wp_get_current_user();
echo '<option value="'.$user->ID.'">'.esc_html($user->user_email).'</option>';
}
}