What is the ruling on drinking Indian kefir, which is produced by fermenting milk with yeasts and bacteria, given that it may contain an ethanol alcohol content of up to 0.5% or more? Is this small percentage of alcohol permissible?

There is no harm in the aforementioned drink, as it is definitely not intoxicating. What was mentioned about the presence of an ethanol percentage as a result of biological processes does not affect the ruling, for such is found in many natural and manufactured foods and beverages. A drink that is originally permissible does not become forbidden unless it reaches the point of intoxication.