It’s a myth, and here’s the easiest way to tell: by the time any of it reaches your kidneys, it will already have been warmed up by the trip through your digestive tract. Water doesn’t have memory. It doesn’t interact with your body based on the temperature it used to be.

Vinegar is an acid, baking soda is a base. When you mix them together, they neutralize each other => salty water. Maybe you can cut out the middle man and drink water with a few shakes of salt.