In Drupal 7 it was not possible to give a user access to administer users without also giving access to all settings and configuration for user accounts. In Drupal 8 this permission has been split into two:
- Administer users: Gives a user the permission to create/edit/delete users
- Administer account settings: Gives a user permission to configure site-wide settings and behavior for user accounts and registration
Drupal upgrade process will grant "Administer account settings" permission to all roles previously having "Administer users" granted. You might want to review permissions after upgrading if you have contrib or custom modules dealing with them (eg. User settings access module).