Steps to reproduce:

1. Run `sudo yum update zabbix-agent` on CentOS 7 machine with Zabbix agent 3.0.29 previously installed via Yum repository.

Result:

warning: /var/cache/yum/x86_64/7/zabbix/packages/zabbix-agent-3.0.30-1.el7.x86_64.rpm: Header V4 RSA/SHA512 Signature, key ID a14fe591: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-ZABBIX

The GPG keys listed for the "Zabbix Official Repository - x86_64" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.

 Failing package is: zabbix-agent-3.0.30-1.el7.x86_64
 GPG Keys are configured as: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-ZABBIX

Additional Notes

This started happening on all 6 of our production CentOS 7 machines about 28-29 hours ago (2020-02-24 10:00 PST). Removing repo entry, cleaning Yum cache, reinstalling repo package, and attempting to update zabbix-agent again results in the same error message.

It's possible that the issue was present before zabbix-agent 3.0.30 was added to the Yum repo, but since we use Chef to manage these servers and they don't attempt to update yum packages until a new version is available, we didn't notice. Version 3.0.29 was installed without issue on these machines, meaning the issue wasn't present on December 20, 2019. I'm happy to provide any further info or test possible fixes.