Unable to use Drush generators

Problem/Motivation

I am unable to generate DTT specific tests using the test generator via Drush.

Drush version : 12.4.3.0
Drupal version : 10.2.4

Steps to reproduce

1. Install DTT and Drush using composer
2. Run ./vendor/bin/drush generate test:existing

Output:

  Command "test:existing" is not defined.  
                                           
  Did you mean one of these?               
      browser-test                         
      kernel-test                          
      nightwatch-test                      
      test:browser                         
      test:kernel                          
      test:nightwatch                      
      test:unit                            
      test:webdriver                       
      unit-test                            
      webdriver-test

Proposed resolution

Ensure Drush commands are loaded and executable, or if this pebcak or user error, possibly update documentation (or reference Drush docs, etc).

Remaining tasks

1. Reproduce the error on another site (I can attempt this

User interface changes

API changes

Data model changes