Chiangkang Vinegar question....
did you open it? If you didnt, no issue.
If you did, it could have evaporated and got stronger. Or, sometimes, vinegars form a mother and the effect is to become sort of watery.
Seriously, I had a bottle of this vinegar that lasted more than a decade, Id estimate and it wasnt even tightly capped.. If it is palatable, I would not sweat the issue.