Could you update the package https://repo.zabbix.com/zabbix/4.0/rhel/9/x86_64/zabbix-release-4.0-2.el9.noarch.rpm to include the correct gpg key RPM-GPG-KEY-ZABBIX-08EFA7DD since it cames with old one RPM-GPG-KEY-ZABBIX-A14FE591

Steps to reproduce:

1. Download official rpm package rpm -Uvh https://repo.zabbix.com/zabbix/4.0/rhel/9/x86_64/zabbix-release-4.0-2.el9.noarch.rpm

yum install zabbix-agent
..

Result:
warning: Signature not supported. Hash algorithm SHA1 not available.
Key import failed (code 2). Failing package is: zabbix-agent-4.0.50-1.el9.x86_64
 GPG Keys are configured as: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-ZABBIX-A14FE591
The downloaded packages were saved in cache until the next successful transaction.
You can remove cached packages by executing 'yum clean packages'.
Error: GPG check FAILED
.

Verification
cat /etc/yum.repos.d/zabbix.repo

1. I've checked the content of /etc/yum.repos.d/zabbix.repo and it shows a wrong gpgkey file A14FE591

[root@jenkins2 zabbix]# cat /etc/yum.repos.d/zabbix.repo
[zabbix]
name=Zabbix Official Repository - $basearch
baseurl=https://repo.zabbix.com/zabbix/4.0/rhel/9/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-ZABBIX-A14FE591

[zabbix-non-supported]
name=Zabbix Official Repository non-supported - $basearch
baseurl=https://repo.zabbix.com/non-supported/rhel/9/$basearch/
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-ZABBIX
gpgcheck=1

Workaround:

1 - I've downloaded the correct from another case https://support.zabbix.com/browse/ZBX-22107

and also, Ive manually change my repo /etc/yum.repos.d/zabbix.repo  to refer it and install run ok.

Thanks

Best regards

Marcia