Display name used for username

@glajman, you can implement hook_openid_connect_userinfo_alter():

/**
 * Implements hook_openid_connect_userinfo_alter().
 */
function [MODULENAME]_openid_connect_userinfo_alter(array &$userinfo, array $context) {
  if ($context['plugin_id'] === 'windows_aad') {
    $userinfo['name'] = $userinfo['email'];
  }
}