I use Yubikey as my 2FA. It works fine, except that every time I forget and close my browser I have to re-enter my Master Password when I have a perfectly good Yubikey plugged into my computer setting at the edge of my laptop or keyboard. To me it would be more secure to use the Yubikey as the Unlock method. It’s unique to me and is what I’d have to use to log back in if I signed out. Having to re-enter the Master password a hundred times a day make me want to simplify the Master password which is not very secure.
I suggest an option for Yubikey users that allow for that to Unlock Bitwarden instead of the Master password once you are completely Logged in.