There’s no one answer for this question.
Some red wine vinegars are vegan, and some are not. It depends on the type of red wine used.
Red wine vinegar is simple to make, combining red wine with a “mother” (bacteria) and water over time. There’s no non-vegan ingredients involved other than potentially the wine itself.
To find out if a specific red wine vinegar is vegan, you’ll either need to know the type of red wine used, or contact the creator.
If you know the type used, plug it into Barnivore (a database of vegan alcohols) and see if it’s vegan.
The easiest way to ensure that your red wine vinegar is vegan is to make your own. While the process is simple, it does take a long time.