For anybody here who brews rather than buys, the homemade version of this has the same culprit from a different direction. Acetic acid bacteria get in, usually through oxygen exposure plus warm temperatures, and turn the alcohol to acid.
So sanitation genuinely matters, keep the ferment cool, and limit air contact once the active fermentation slows rather than leaving a half-empty vessel open to the room. If a homemade batch smells strongly of vinegar it is usually a start-again rather than a rescue.