What is this strange problem?

This problem appears continuously and permanently when I do a reboot of the server, it appears to me that I have deleted the panel and reinstalled it, and it also shows what this problem is and how it can be solved in detail?

Welcome @ward Happy you are here

The issue is: Unable to register authentication agent: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Cannot determine user of subject

Run the commands line by line:

# add user to the group
$ groupadd -g 23 nohidproc
$ usermod -a -G nohidproc polkitd
$ mount -o remount,rw,hidepid=2,gid=nohidproc /proc
$ systemctl restart polkit
# nano /etc/fstab or run it directly
$ echo "proc /proc proc defaults,hidepid=2,gid=nohidproc 0 0" >> /etc/fstab
# add new mount
$ mount -a
$ systemctl restart polkit

This is just a waring from linux you don’t have to worry much about this