That can be the transaction fee charged. Do the calculation according to the Zebpay guide and validate the received amount.

E.g when you sell/transfer bitcoin to a different address, a transaction fee is charged.

Quoted from zebpay. Zebpay transaction fees on selling bitcoins

"You will be charged a bitcoin network fee when you send bitcoins to a bitcoin address depending on the number of bitcoins you send. Fees are dynamic and updated on daily basis. Please check your app for latest fees.