Error with lightdm-gtk-greeter-settings-pkexec

I have an error trying to run lightdm-gtk-greeter-settings-pkexec on my rpi-400

If I try to run it from xfce menu nothing is displayed and trying to run it from terminal I have this error message:

lightdm-gtk-greeter-settings-pkexec                                                    ✔ 
No protocol specified
Unable to init server: Could not connect: Connection refused
No protocol specified
Unable to init server: Impossibile connettersi: Connection refused

(lightdm-gtk-greeter-settings:99033): Gtk-CRITICAL **: 21:42:13.115: _gtk_style_provider_private_get_settings: assertion 'GTK_IS_STYLE_PROVIDER_PRIVATE (provider)' failed

(lightdm-gtk-greeter-settings:99033): Gtk-CRITICAL **: 21:42:13.115: _gtk_style_provider_private_get_settings: assertion 'GTK_IS_STYLE_PROVIDER_PRIVATE (provider)' failed

(lightdm-gtk-greeter-settings:99033): Gtk-CRITICAL **: 21:42:13.115: _gtk_style_provider_private_get_settings: assertion 'GTK_IS_STYLE_PROVIDER_PRIVATE (provider)' failed
 /usr/bin/lightdm-gtk-greeter-settings-pkexec: riga 13: 99033 Errore di segmentazione (core dump creato) pkexec "${APP_PATH}" "$@"

This is the version installed:

pamac info lightdm-gtk-greeter                                            ✔  4s  
Name                  : lightdm-gtk-greeter
Version               : 1:2.0.8-1
Description           : GTK+ greeter for LightDM
URL                   : https://github.com/Xubuntu/lightdm-gtk-greeter
Licenses              : GPL3 LGPL3
Repository            : extra
Installed Size        : 340.3 kB
Depends On            : gtk3 lightdm
Make Dependencies     : exo git gobject-introspection intltool xfce4-dev-tools
Packager              : Arch Linux ARM Build System <builder+n1@archlinuxarm.org>
Build Date            : 07/04/20
Install Date          : 02/27/21
Install Reason        : Explicitly installed
Signatures            : Yes
Backup files          : /etc/lightdm/lightdm-gtk-greeter.conf