"Most of what I loved about Drupal the product can still be found in Backdrop and Backdrop keeps getting better with each release. I'm happy that Drupal 9 exists and I wish it a long and prosperous life, but my personal commitment is in meeting the needs of the small organizations and businesses that I believe Drupal 9 has left behind."
https://www.triplo.co/blog/backdrop-cms-providing-soft-landing-drupal-7-sites