A good example here is 1Password, which stores passwords and also allows storing TOTP. Which means the something I know is stored in the same places as somethi

A good example here is 1Password, which stores passwords and also allows storing TOTP. Which means the something I know is stored in the same places as something I have. Granted it is protected by encryption, and another password, but it definitely increases the attack surface. If the computer is compromised it becomes much more possible to get access to both of these items than if it was a security key, physical authenticator or even on a different device.