Do you mean yubikeys as in 2FA for bitwarden (etc)? Or yubikeys as in requiring a challenge response to authenticate into a vault?
AFAIK, 2fa is just another step before a server - executing code as it was intended - will return vault data to you. It doesn't protect against vault disclosure aka ransomware / data breach, similar to the Lastpass breach.
As for yubikey to authenticate into a vault, I'm not sure if it's something that actually strengthens the knowledge required to get into a vault (assuming you have the vault data yourself). Like, is it actually another secret required to decrypt the vault data? Or is it just another step the server verifies before it grants you access to download the vault data (and then decrypt client-side)?
AFAIK, 2fa is just another step before a server - executing code as it was intended - will return vault data to you. It doesn't protect against vault disclosure aka ransomware / data breach, similar to the Lastpass breach.
As for yubikey to authenticate into a vault, I'm not sure if it's something that actually strengthens the knowledge required to get into a vault (assuming you have the vault data yourself). Like, is it actually another secret required to decrypt the vault data? Or is it just another step the server verifies before it grants you access to download the vault data (and then decrypt client-side)?