In a large, complex society of billions of people, weird things happen.
Couldn’t smell it when it was handed to you , ya right
and if that McDonald’s doesn’t use what ever is in the cup ?
I once got a rubber fixture from a shake machine in my vanilla shake at McD.
She’s not guilty!
I had a two-inch roach in a glass of ice water once !
Gross stuff happens
The machine is cleaned on a regular basis (which is why their coffee tastes better then other places). Usually the machine is left open when the cleaning is going on so you can not make a coffee drink. But it just takes one newbie to push the door closed and you can have an incident.
They obviously need a better lockout/tagout procedure.
I'm sure they're fine. It's a cleaner approved for use in food service, so it's probably minimally toxic.
In any case, when a machine is out of service it should be red-tagged, so that even the new guy just starting his shift will know not to use it.