running the tests the Drupal tests the way the testbot does

[2dareis2do]

I am looking at the drupal docs https://www.drupal.org/docs/automated-testing/phpunit-in-drupal/running-phpunit-tests#run-like-testbot.

From what I see the testbot does run on the 8.x branch e.g. in .lando.yml we have

php /app/web/core/scripts/run-tests.sh --php /usr/local/bin/php --url https://drupal-contributions.lndo.site --color --verbose

also

https://www.youtube.com/watch?v=vVpKCQZKNtM

however on 9.x and 10.x it looks like this option has now gone and seems to be replaced with either core-check and nightwatch.

Please can someone explain the reason for this. I would like to run the tests the way that Drupal testbot does but it seems this is only on 8.x branch for some reason?