RADIUS: client username 'UPPERCASE@domain.enterprise.com' remapped 'lowercase@domain.enterprise.com' and vice-versa

Hi everyone!
My PrivacyIDEA installed and configured RADIUS plugin. I have OpenVPN Access Server (OpenVPN-AS) application used authentication method is RADIUS and connected to PrivacyIDEA server for authentication OpenVPN-AS users. I also configured REALMS on PrivacyIDEA admin page webui.
On my OpenVPN-AS server log, I saw the following log lines:

2023-01-07T17:19:55+0700 [stdout#info] RADIUS: client username ‘UPPERCASE@domain.enterprise.com’ remapped ‘lowercase@domain.enterprise.com’
2023-01-07T22:31:11+0700 [stdout#info] RADIUS: client username ‘lowercase@domain.enterprise.com’ remapped ‘UPPERCASE@domain.enterprise.com’

My PrivacyIDEA server installed on Ubuntu server 20.04.3 LTS and here is my version of PrivacyIDEA/RADIUS plugin:
privacyidea-nginx/now 3.6.3-1focal all [installed,upgradable to: 3.8-1focal]
privacyidea-radius/now 3.4.1-2focal all [installed,upgradable to: 3.4.2-1focal]
privacyidea/now 3.6.3-1focal amd64 [installed,upgradable to: 3.8-1focal]

freeradius-common/focal-updates,focal-security,now 3.0.20+dfsg-3ubuntu0.2 all [installed,automatic]
freeradius-config/focal-updates,focal-security,now 3.0.20+dfsg-3ubuntu0.2 amd64 [installed,automatic]
freeradius-utils/focal-updates,focal-security,now 3.0.20+dfsg-3ubuntu0.2 amd64 [installed,automatic]
freeradius/focal-updates,focal-security,now 3.0.20+dfsg-3ubuntu0.2 amd64 [installed,automatic]
libfreeradius3/focal-updates,focal-security,now 3.0.20+dfsg-3ubuntu0.2 amd64 [installed,automatic]
privacyidea-radius/now 3.4.1-2focal all [installed,upgradable to: 3.4.2-1focal]

I have two question:

  • What is purpose of this remap username on RADIUS?
  • How can I remap all username to lowercase only? Is it possible and how can I archive this?

Thank you so much for your help!

Please anybody can help me on this.

This is not done by the privacyIDEA plugin.
This must happen somehwere else in your own RADIUS configuration.

Run radius in debug mode via

 freeradius -X