Airtel started levying usage fees on electricity bill payments while using Airtel Axis credit card on its app. Might add the same for other bill payments also.
And as out of 250 limit, we already gave extra amount of usage fee of 56 rs.( ~2.24% 2500 of max cashback amount), so practically max CB is Rs. 194(250-56).
Which is significantly lesser that 300 CB when card started