[MM3-users] Username being set to givenname for socialaccount login

I have a new mailman3 install setup with Okta as a social application. This is working well for logins and data comes through as expected, but for some reason the username is being set at to a lowercase version of the given_name. The Extra data on the social users in the admin interface looks good, so I don’t think it’s a problem with the attributes coming from Okta.

We have tried a number of variations on the below setting, but that all of them other than the default of “username” end up with the username being empty. ACCOUNT_USER_MODEL_USERNAME_FIELD = “email”

Any direction would be welcome.

Thank you!