@thongnguyenminh I made a solution with a post-save filter.
//Remove white space at the end of wysiwyg strings
add_filter('acf/update_value/type=wysiwyg', function($value){
//preg_replace below only works if the wpautop function has been run
$value = wpautop($value);
$value = force_balance_tags($value);
$value = preg_replace('/<p>(?:\s| )*?<\/p>/i', '', $value);
$value = trim($value);
return $value;
});
