Strange problem during logout from Ubuntu

Below telnet session of login/logout from Mageia tu Ubuntu

Code:[maciek@Piotr ~]$ telnet nano
Trying 192.168.0.25...
Connected to nano.
Escape character is '^]'.
Ubuntu 16.04.7 LTS
NanoPi-NEO login: nano
Password:
nano@NanoPi-NEO:~$ ls -la
total 36
drwxr-xr-x 4 nano nano 4096 lut 13 00:58 .
drwxr-xr-x 5 root root 4096 lut 12 00:41 ..
-rw------- 1 nano nano 502 lut 13 01:47 .bash_history
-rw-r--r-- 1 nano nano 220 wrz 1 2015 .bash_logout
-rw-r--r-- 1 nano nano 3771 wrz 1 2015 .bashrc
drwx------ 2 nano nano 4096 lut 12 00:47 .cache
-rw-rw-r-- 1 nano nano 0 lut 13 00:31 .hushlogin
-rw-r--r-- 1 nano nano 655 cze 24 2016 .profile
drwx------ 2 nano nano 4096 sie 18 2022 .ssh
-rw-r--r-- 1 nano nano 0 lut 13 00:32 .sudo_as_admin_successful
-rw------- 1 nano nano 782 lut 12 23:53 .viminfo
nano@NanoPi-NEO:~$ logout
mount: only root can use "--options" option
Connection closed by foreign host.As you can see, during logout the "mount" command signals an error.
The problem is that none of the files in the user's home directory (which are listed) contain the "mount" command.
So it must be something globally defined.
The problem does not occur during SSH sessions, only during TELNET sessions.
Does anyone out there know the reason? Any idea?

I explain that I use telnet daemon on Ubuntu installed on RPi because it is a "last resort solution" for me. I normally use SSH.
The system is installed on eMMC (not on SD-card) and once I damaged the SSH configuration, which made it impossible to log in to the system.So I had to reinstall the system