Regression: unable to create a new user through Admin Aera

Summary

When an administrator wants to create a new user through the Admin Aera, GitLab always respond with the following error:

The form contains the following error:
    Username can contain only letters, digits, '_', '-' and '.'. Cannot start with '-' or end in '.', '.git' or '.atom'.

Here are the details I put to create the user:

• username: jdoe
• name: John Doe
• email: john.doe@test.com
• cannot create group
• access level: regular and external

I tried other simple usernames, but still get the same error.

Tested in GitLab versions 15.2.2 and 15.3.1.

More details:

• GitLab enterprise edition (free tiers)
• No link to any other source like Active Directory (users are stored directly in GitLab)
• Installed in a Docker container (official image gitlab/gitlab-ee:15.3.1-ee.0)

Let me know if I there is more information needed.