Not if you have a password-protected Yubikey with GPG/RSA signing, encryption, and authentication keys and a second backup Yubikey with the same keys. If you lo

Not if you have a password-protected Yubikey with GPG/RSA signing, encryption, and authentication keys and a second backup Yubikey with the same keys. If you lose one, order two more ASAP, use the backup key to change your keys in every machine and revoke that key (thereby rendering the lost Yubikey and your backup useless). Wait for the new Yubikeys to arrive, generate new keys, change all machines to these new keys, and revoke the temporary keys you generated.