20W charger authenticity

There is no way any of us here, by just looking at an image, can guarantee what you have is original or not.

Did you purchase this power adapter directly from Apple or an Apple Authorized Reseller? If so, then it would be an original. If not, then there is a possibility that it is a fake.

Ref: About Apple USB power adapters - Apple Support

I have two of these that I ordered directly from Apple in the U.S. and both show country of origin as China, but as stedman1 has pointed out, Apple can source their electronics from multiple countries and India is among them.

Apple has manufacturing facilities in several countries, including India, China, Vietnam.