set_user_role
Action Hook: Fires after the user’s role has changed.
Source: wp-includes/class-wp-user.php:652
WP_User::__get()
Method: Magic method for accessing custom fields.
Source: wp-includes/class-wp-user.php:305
WP_User::level_reduction()
Method: Chooses the maximum level the user has.
Source: wp-includes/class-wp-user.php:673