Without site aliases, "drush sql:sync" fails

Question

I run into an issue that the use of an alias returns correct values, but without alias or from remote, I miss the DB connection. Furthermore, the root directory is wrong. The missing DB connection prevents a drush sql:sync run.

Alias file:

$drush sa
'@self.dev':
  root: /var/www/html/xyz
  uri: 'https://www.abcdef.com'
  ssh:
    options: '-i xyz.pem'
  paths:
    drush-script: /home/ubuntu/vendor/bin/drush
    files: themes
  command:
    core:
      rsync:
        options:
          mode: rlptz

running drush status somewhere:

$ drush st
PHP binary    : /usr/bin/php7.4
PHP config    : /etc/php/7.4/cli/php.ini
PHP OS        : Linux
Drush script  : /home/ubuntu/vendor/drush/drush/drush
Drush version : 10.6.2
Drush temp    : /tmp
Drush configs : /home/ubuntu/.drush/drush.yml
                /home/ubuntu/vendor/drush/drush/drush.yml

running drush status with alias:

$ drush @dev st
Drupal version   : 9.4.5
Site URI         : https://www.abcdef.com
DB driver        : mysql
DB hostname      : 127.0.0.1
DB port          : 3306
DB username      : qwertzy
DB name          : drupal
Database         : Connected
Drupal bootstrap : Successful
Default theme    : xyz
Admin theme      : seven
PHP binary       : /usr/bin/php7.4
PHP config       : /etc/php/7.4/cli/php.ini
PHP OS           : Linux
Drush script     : /var/www/html/xyz/vendor/drush/drush/drush
Drush version    : 10.6.2
Drush temp       : /tmp
Drush configs    : /home/ubuntu/.drush/drush.yml
                   /var/www/html/xyz/vendor/drush/drush/drush.yml
Install profile  : standard
Drupal root      : /var/www/html/xyz/web
Site path        : sites/default
Files, Public    : sites/default/files
Files, Private   : /var/private
Files, Temp      : /tmp

running drush status in the drupal root: ! Wrong drupal root returned

cd /var/www/html/xyz
$ drush st
PHP binary    : /usr/bin/php7.4
PHP config    : /etc/php/7.4/cli/php.ini
PHP OS        : Linux
Drush script  : /home/ubuntu/vendor/drush/drush/drush
Drush version : 10.6.2
Drush temp    : /tmp
Drush configs : /home/ubuntu/.drush/drush.yml
                /home/ubuntu/vendor/drush/drush/drush.yml
Drupal root   : /var/www/html/xyz/web/web

called from remote with alias: ! Again wrong drupal root returned

ubuntu@ip-172-26-13-167 ~ $ drush @dev st
PHP binary    : /usr/bin/php7.4
PHP config    : /etc/php/7.4/cli/php.ini
PHP OS        : Linux
Drush script  : /home/ubuntu/vendor/bin/drush
Drush version : 10.6.2
Drush temp    : /tmp
Drush configs : /home/ubuntu/.drush/drush.yml
                /home/ubuntu/vendor/drush/drush/drush.yml
Drupal root   : /var/www/html/xyz/web/web
Connection to 172.26.10.26 closed.

Any advice appreciated how to fix this.

Answer 1

I've commented because there are some things in your installation that don't add up. But the comments lead to nowhere so I try to make it more clear in an answer.

In a comment you say:

Drush launcher is installed.

but then "running drush status somewhere" should result in:

The Drush launcher could not find a Drupal site to operate on. Please do *one* of the following:
  - Navigate to any where within your Drupal project and try again.
  - Add --root=/path/to/drupal so Drush knows where your site is located.

So the question is, what is this globally installed script which runs when you are in a Drupal root directory

/home/ubuntu/vendor/drush/drush/drush

when it is not the Drush Launcher?