Block changes on logon language for users

Hi SAP Gurus

I am trying to restrict users from changing their language settings on their own users. I cannot find any relevant authorization object for this.

I have then tried to make and block of the field in SHD0 but that did not work either (I have tried with screen variant SU0_SUID_MAINTENANCE_1100 / program SAPLSUID_MAINTENANCE but that did not work).

Any clues on how to do this?