If you can't understand one thing that does not means it's a mess.
For gyftr portal you get 5% cashback for CC txn that is credited directly to the CC Statement, no points is credited for them.
For Payzapp app it is also same for CC.

For DC, if you buy using gyftr portal 5% cashback is credited as points, if you buy using payzapp app it is credited as 3% payzapp cashpoints (payzapp wallet).

HDFC DC mentions 5% Cashback on Payzapp/Smartbuy as a benefit.
This benefit is exclusively for Millenia Debit only. that is you get 5+5% cashback if bought using gyftr portal.

HDFC CC does not mention 5% Cashback on Payzapp/Smartbuy as a benefit.
Yeah it doesn't mention because it is not a card related features, all HDFC Cards are eligible for 5% cb.


Answer to last questions.

For Millenia DC, you get 5+5% if bought using gyftr and 5+3% if using payzapp app.
For Millenia CC, you get 5% direct cb + 1% card benefits. This limit is different from 1000 limit of 10 brands which gives 5%

1. If I do the transactions (Rs. 40,000) below in a month via Millennia CC, how much cashback would I get on the card?
   Rs. 20,000 - Directly on Amazon, Rs. 20,000 - Amazon Shopping Voucher via GYFTR
   
   You will get 5% that is 1000 for amazon txn, 5% that is 1000 for asv via gyftr + 1% that is 200 for using millenia cc on gyftr, that totals to 2200Rs.
   
   For above same scenario you will get 1400 cb if used via millenia dc and gyftr portal.
   
   
   
   And at last if any company is giving any cashback then it can not be hidden

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