lot of the vinegars used in 'preserving' in bottles of onions/beetroot/.... are not very strong and do go off along with the other contents of jars, hence, we learned to our cost, you do have to keep them in the fridge once opened ... like the fake malt vinegars chip shops have.
so all vinegars are not the same .... but sep 21 unless it has spent winter in Australia doubt that's an issue.