I think you’re right, that someone didn’t clean the machine properly and left some sterilizer in it. Back when I worked in fast food, 50-some years ago, the manager would have found out who did it and made sure that person never did it again, possibly by administering physical therapy behind the carwash next door. This DQ manager really screwed up, and will pay for it.
“Back when I worked in fast food, 50-some years ago, the manager would have found out who did it and made sure that person never did it again, possibly by administering physical therapy behind the carwash next door.”
If I were the employee back at that age, the manager had better really be on his game.