Whenever login to debian OS via ssh will get this message:
Linux ds1821-virtual-debian 5.10.0-15-amd64 #1 SMP Debian 5.10.120-1 (2022-06-09) x86_64 The programs included with the Debian GNU/Linux system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law.
As Joan notes,
motd is the key. The Debian wiki has good information on how the motd file is generated at boot and how to modify it. Check out the How to keep your /etc/motd from being overwritten section to make permanent motd changes.
If you just want to disable it for your user, create a
.hushlogin file in your home directory: