See: https://docs.fedoraproject.org/en-US/fedora-silverblue/installation/#manual-partition Here it does not mention /boot/efi, but https://docs.fedoraproject.org/en-US/fedora-silverblue/troubleshooting/#_unable_to_install_silverblue_on_efi_systems Here it asks to mount on /boot/efi I suggest the wording in manual partitioning be clarified to suggest you can mount /boot/efi.