We’re investigating replacing email address with username as user id in using custom database connections for user authentication and want to know if the rules of allowed characters in this doc apply to custom database connections as well.
When using custom databases, the behavior is slightly different depending on whether you have import mode enabled.
Import mode enabled
The behavior replicates the regular Auth0 database, although the messaging may only be visible in the tenant logs.
Import mode disabled
The rules for allowed characters do not apply. Any characters are acceptable for the username.