High CPU on Primary server due to excessive zbxuser SSH logins

[User64]

Hi everyone,
I'm troubleshooting high CPU spikes on a primary server caused by excessive logins from our zbxusermonitoring account. Interestingly, we have an identical secondary server that behaves completely normally (~2 logins/min, low CPU).
What we have already verified and ruled out:

• Templates & Macros: Both servers use the exact same templates and macros.
• Host Groups & Actions: Primary originally had 3 extra host groups, but removing them to match the secondary server made no difference, and no Trigger Actions/Remote Commands are firing.
• Duplicate Hosts: Both sites have an identical .local host entry (not monitored by a proxy) alongside the main proxy-monitored host.
• Target Environment: Both servers use an identical restricted shell environment for zbxuser (SNMP is not used on either).

Despite identical Zabbix configurations, why would the primary server experience drastically more zbxuserlogin sessions and CPU spikes than the secondary? Are there specific Zabbix poller/retry behaviours I should check?
Thanks in advance!