Problem statement
Do you maintain the previously used auth0_id (auth0|xxxxxxxxxxxxxxxxxxxxx) when an account is deleted?
When another user creates an account, is there any possibility of duplicating the auth0_id used in the past?
Solution
We don’t maintain older/used user ids.
If not explicitly specified, our ids are generated via Mongo document Ids which are incrementing, so they should be unique for new users.
If a custom user_id is specified, then you could re-make a user with the same user_id. They would still have a unique/new document ID in applicationUser and users, but the user_id they would see (auth0|xxx ) could be the same.