how do I change realm login format in sssd?

I’m trying to figure out how to change my realm login format to allow for lowercase but currently it just seems to work with uppercase?

realm list
domain
  type: kerberos
  realm-name: domain
  domain-name: domain
  configured: kerberos-member
  server-software: active-directory
  client-software: sssd
  required-package: oddjob
  required-package: oddjob-mkhomedir
  required-package: sssd
  required-package: adcli
  required-package: samba-common-tools
  login-formats: %U
  login-policy: allow-permitted-logins

I would like to utilize login format %u instead?