Issue:

On AlmaLinux 8.9, running dnf update will result in a GPG Check Failed error:

Importing GPG key 0xC21AD6EA:
 Userid     : "AlmaLinux <packager@almalinux.org>"
 Fingerprint: E53C F5EF 91CE B0AD 1812 ECB8 51D6 647E C21A D6EA
 From       : /etc/pki/rpm-gpg/RPM-GPG-KEY-AlmaLinux
Key imported successfully
Import of key(s) didn't help, wrong key(s)?

Solution:

To resolve this, remove cached packages with the command dnf clean packages and then run the following command: 

rpm --import https://repo.almalinux.org/almalinux/RPM-GPG-KEY-AlmaLinux

Then you can run dnf update like normal.

Cause:

The GPG key for the xfsdump package was not installed, resulting in a GPG check failure during the package installation, which was resolved by importing the necessary key from the AlmaLinux repository.