A lot of the comments are making the assumption that the buttons are telling the truth about being different sizes, but I’ve flushed plenty of toilets where both buttons do a full flush. If you can’t tell the difference after experimenting, it might just be broken or cheap tat.
If you’re doing things properly, you’ll know your Microsoft account password or have it in a password manager (and maybe have other account recovery options available like getting a password reset email etc.), and have a separate password for the PC you’re locked out of, which would be the thing you’d forgotten. If someone isn’t computer-literate, it’s totally plausible that they’d forget both passwords, have no password manager, and not have set up a recovery email address, and they’d lose all their data if they couldn’t get into their machine.