Steps to reproduce:

• configure /_home/zabbix as the home of the zabbix user (on server and destination)
• create key pair on the server, using ssh-keygen -t ed25519, no pass phrase
• copy public key to destination using ssh-copy-id
• login as zabbix onf the server and verify ssh connection on the command line using "ssh zabbix@destination true"
• setup ssh-agent item for destination, Key is "ssh.run['NFS health check']", username zabbix, public key is id_ed25519.pub, private key is id_ed25519, script is /bin/hostname
• verify latest data for destination in Zabbis

Result:
Looking at latest data for destination there is an error popup for 'NFS health check saying

Cannot establish SSH session: kex error : no match for method server host key algo: server [rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519], client [ssh-rsa]

This means zabbix server and ssh server (openssh 9.7) could not agree upon common ciphers to verify the host key.

Expected:
Zabbix server should support modern ciphers for ssh connections. ssh-rsa has been deprecated some time ago. OpenSSH 9.8 won't include the deprecated ciphers anymore (using default build time flags).