Molded Biltong that supposed to be fresh expiring on December 2025 but full of mold after 4 days from purchase

Bought Kalahari biltong from checkers Weltevreden in Mitchells Plain on the 15th October got at home 4 days and opened it today ate of it only to notice there are mold on the biltong it supposed to be fresh because the expiring date is only December 2025. What horror are these big stores doing to our health how could a product mold so quickly that supposed to be fresh?