It's hard to know what kind of information could leak in advance. It gives the attacker more information on your surrounding. They could take mug shots to craft

It's hard to know what kind of information could leak in advance. It gives the attacker more information on your surrounding. They could take mug shots to craft a fake profile. Or maybe see a credit card flashing by... it doesn't have to be blackmail-worthy material necessarily. Granted, if the attacker can access the webcam then most likely your system is compromised, 1password is compromised (including the 2nd factor as advertised on the site), so you might have bigger problems already. It all depends on the intent of the attacker.