Give an example of people who suffer from loss during an unanticipated deflation.

Any borrower who borrows money from creditors at a fixed interest rate suffers from loss during an unanticipated deflation.

e.g. individuals who borrow mortgage loans from banks, etc

(Note that investors who hold inflation-linked bonds instead of cash do not suffer from loss this time because inflation-linked bonds guarantee a minimum percentage of interest rate even when there is no inflation.)