There is an easier way to replicate: just type "{{subst:#uic:Example}}" in any page，and it will turn out to be"<button type="button" aria-label="打開用戶信息卡" aria-haspopover="dialog" class="ext-checkuser-userinfocard-button cdx-button cdx-button--action-default cdx-button--weight-quiet cdx-button--icon-only" data-username="Example" hidden=""></button>"

See [[zh:Special:Diff/94090557]], it's in the wikitext code.

@cscott For example, the main page of Chinese Wikipedia.

Maybe we can just remove all rights from accountcreator, like cuwiki and other several private wikis did.

I don't think it's necessary to allow event-organizers to remove eventparticipant group from themselves, since they can remove eventparticipant group from anyone.

In T414049#11551796, @Wargo wrote:

Difference between user_type should be explained.

"user_type" is the type of user who did the edit or the operation. "account_type" is the type of the account which is being created in the "createaccount" or "autocreateaccount" operation. During the "autocreateaccount" operation, the users from other wikis are identified to be unregistered users by the abusefilter, but the "account_type" parameter of the operation is "named" for the abusefilter.