Add SocketMode=0600 to the per-user dbus.socket
The default SocketMode for systemd.socket is 0666, See: SocketMode, so the mode of per-user dbus.socket (/run/user/UID/dbus) is set to 0666. However, the runtime directory is set to 0700 by systemd, the last two 66
s are not needed IMHO. Please consider change it to 0600 by adding SocketMode=0600 in dbus.socket.