How to manage multiple drupal 7/8 sites with multiple drush versions
I assume the command above is run locally and it connects to the dev server? On the dev server you have the phar-installed global Drush 8 and the site-local Drush 9. From the debug backtrace you see that it starts with launching the global Drush 8 and then at the end it uses some functions from the site-local Drush since those are included when Drupal 8 bootstraps. Not strange that it doesn't work. And to make it even worse the: The phar-installed global Drush is too old - Drush 8.14 is clearly needed.

It might work to upgrade the phar-installed Drush 8 to 8.15, but why not use Drush Launcher (which is recommended) and install in globally instead of Drush. It even supports a fallback to a globally installed Drush of your liking.