I love how I have 20 years of #Drupal experience and every year I know less and less about how it works now.

Can you no longer alter a form array in #Drupal to just add a destination? Do you really have to define a whole submit function now?

https://www.drupal.org/docs/extending-drupal/contributed-modules/contributed-module-archive/contrib-modules-for-building-the-site-functionality/forms/basic-form-alterations/redirecting-a-form