If you had to ruin an entire app/website by integrating automatic logout, which app would you choose to achieve maximum damage?

My guess is 2fa code apps. Why you ask? Because blizzard already did it. They use their own proprietary 2fa code generator app called battle net, so I have to use it. So after a few months/years of casually not using anything remotely connected with Mr. And Mrs. „Muttermilchknacker”

, I finally decided to try Overwatch 2 again, and when I tried to use my login app to confirm my login, I found myself logged out. And when I tried to log in again, I had to use the Authenticator, which I was logged out of, to use my authenticator, in order to log into the authenticator, in order to use the authenticator, in order to log into my authenticator (I could keep going like this forever)