This action can be for deleting the user cache. In most cases, the do_action should be done allowing the wpDiscuz to delete its own caches.
Changelog
since 7.3.0 version
Parameters
1. $userKey – the keys of the user. For the user the caches will be deleted.
The key for the registred users is: {user_id}_{user_email}_{display_name}
For the guest: 0_{comment_author_email}_{comment_author}).
If it’s missing it’ll work for all users.
Usage
do_action("wpdiscuz_reset_users_cache", $userKey);