Can you explain the password for Username on the "1Password Account" key in my vault?

I have an update. Turns out although the key "1Password Account" has a password in it, that password did not match the password for my account (duh). It seems that when I hit the "Change Password" button, got the Change Password popup where you're asked to enter your old password, your new password and confirm the new password. With each entry on the new password, 1Password asks to save the password, which apparently I answered 'yes'. This I believe created the '1Password Account' key and filled in my login password. But then why didn't the password stick? Best I can guess is that I hit the save password button but didn't properly execute the 'Change Password' in the end (I'm guessing here). So the key got updated in the vault but the password did not.

As for my IOS apps, well apparently they didn't have the new password and instead were relying on FaceID against the old password to login me in there. Once I resubmitted the change, my IOS devices now required me to reenter my password which was the new password.

So problem is somewhat solved, but back to my original question. What is the password for in the '1Password Account' key in my vault? It seems to be detached from the login process, so what is it?