With REHL 9 and AlmaLinux 9 and presumably other RedHat derivative, DES is no longer available for net-snmp communication. DES or Data Encryption Standard is an old encryption standard and has been superseded by AES.
So when you try running snmpwalk with “-x DES” option, you get the following error
Invalid privacy protocol specified after -3x flag: DES USAGE: snmpwalk [OPTIONS] AGENT [OID] Version: 5.9.1
To fix the issue, you’ll need to upgrade your devices to AES.