The free-with-small-rate-limits designator was "experimental", not "preview". I think the distinction between preview and full release is that the preview mode

The free-with-small-rate-limits designator was "experimental", not "preview". I think the distinction between preview and full release is that the preview models have no guarantees on how long they'll be available, the full release comes with a pre-set discontinuation date. So if want the stability for a production app, you wouldn't want to use a preview model.