Enable 2 letter avatars

In Nextcloud 19 there should be the possibility to enable 2 letter autogenerated avatars. How do I enable this?

Still nobody got a hint how to activate this function in Nextcloud 19?

If a user has a two-part display name, the avatar will have two letters.

When linking to a LDAP (AD) user directory, this happens automatically.
I think this is the case for a few NC versions already…