Change a node's type/bundle keep the old type/bundle in field tables

I need to change the bundle/type of some nodes. I tried https://www.drupal.org/project/convert_bundles but there was no way to select just a few nodes and change the bundle/type so I tried the very simple way:

  $node = Node::load(123);
  $node->set('type', 'new_type_name');
  $node->save();

This seems to work: the content type of the node changed. But when I look at the field's database tables there is still the old type/bundle name in the column "bundle" for each field of this node. This only changes when I actually change the field in the node edit form and save it.

My question: does somebody know if there are any sideeffects when there are fields connected to a node where in the field's table is the wrong bundle name stored?

As commented by @johnSmith, purging is the problem here, but there are two different purging processes. The first one is triggered when the field storage is removed and the entire table is marked as deleted and purged in cron runs, this should still work. The second one is triggered when a field is removed only from a bundle. Then the affected field items are marked as deleted and purged. This doesn't work any longer. But even if this doesn't bother you and you don't notice other side effects, I still would recommend to update every field table and leave the entity tables in a consistent state as described in the latest comment.