Embedding iFrame of a cross domain .app or .ai is throwing errors and not allowing the site to embed

We're attempting to add an iframe of Chatterbox.vercel.app or Chatterbox.ai to a Sharepoint site page.  We've added it to the HTML allowed sites but its still throwing errors.  The cross domain of .ai we thought was maybe too new for Sharepoint version.  We're at a loss.  Any ideas?