The function db_installer_object() has been deprecated

The function db_installer_object() has been deprecated and will be removed before the release of Drupal 11.0. There is no replacement for this function.

In Drupal 9 and before the installer object could be in different locations depending on the type of database driver used. In Drupal 10 and higher all database drivers are located in a module. All database drivers have the same namespace formula. Which is Drupal\{module_name}\Driver\Database\{driver_name}. Because of this change is the replacement code for the function is:

  // Before
  $installer = db_installer_object($driver, $namespace);

  //After
  $installer_class = $namespace . "\\Install\\Tasks";
  $installer = new $installer_class();