# rpm-ostree rebase fedora:fedora/34/x86_64/silverblue
error: Commit 60c89703aaf58f4c05c7cabcffa8b8ca581c8d22460c195d63d0ac8f5249e2d0: GPG signatures found, but none are in trusted keyring
視察の後、次にて解決。
# /bin/rpm -i fedora-gpg-keys-35-0.4.noarch.rpm