What I have understood is that they have considered Payzapp for 5% category for all transactions done on Payzapp except wallet loading. That's why Credit Card Bill Payment is also considered.
The concern is that what is the capping, it says 2000 RP/month if its 1:1 then for 40k Bill Payment you earn 2k which is amazing but it is sounding too good to be true honestly. There must be some catch or I have mis interpreted something.