Why does an underscore mysteriously appear at the front of a User's Username?
|Knowledge Article Number||000205672|
|Description||User records seem to be updating and an underscore, "_", is being added to the beginning of the username.|
|Resolution||This occurs when you disable a Partner or Customer Portal Account. When the Account is disabled, all related Portal User records become "inactive" and the username is updated to append an underscore to the front. This is so you can use that username again in the future, if needed
NOTE: Same behavior can be seen with Community licenses (Customer Community / Customer Community Plus)