We are running CiviCRM 5.13.4 on the lastest version of Wordpress. We have just moved over to Wordpress, so by rights there shouldn't be many Wordpress users registered.
We have CiviCRM Wordpress Member Sync installed. We have two types of membership - Full, and Associate. Wordpress Member Sync is setup to change the role on any matching user to either 'Full Member' or 'Associate Member'.
It is not set to "Create WordPress Users - Create a WordPress User for each Membership when one does not already exist."
However, bit by bit the number of users in our Wordpress system is climbing - and it's only members who are having accounts mysteriously auto-created. Yesterday there were 180 members with user accounts, today 227.
We can't think of anything we're doing that would trigger these accounts to be created, and as every account has some sort of membership attached to it we can only think that the culprit is something buggy in CiviCRM Wordpress Member Sync, but could it be anything else?