What is the value of "Drupal user" in Drush status for?
The value "Drupal user" is the user the Drush command is run as. You can supply a (valid) user name to any Drush command using -u - for example drush status -u admin. Your implicit question, why did the status command suddenly report "anonymous" as the user, I can not answer. You would have examine the code you pulled - maybe something in the settings?