If you see logs like this:
GPG key at file:///etc/pki/rpm-gpg/RPM-GPG-KEY-nobara-appstream-pubkey.gpg (0x0FE970A2) is already installed The GPG keys listed for the "nobara-appstream" repository are already installed but they are not correct for this package.
Try manually updating the repository keys without doing gpg check:
sudo dnf update fedora-gpg-keys --nogpgcheck --refresh sudo dnf update nobara-gpg-keys --nogpgcheck --refresh
This should fix gpg checks in the future because it updates the keys required to do so.