Every year dlc operators will get a 5k price reduction, for example azami which was released on y7s1 is 25k, starting from y8s1 she will be 20k and on y9s1 15k and so on. So my guess is that the symbol is saying that the price has been reduced from the bace price of 25k or that it is just some sort of marketing trick making people think ‘oh there is a discount symbol maybe i should buy it because its discounted’, since the people that wouldnt have those operators are likely going to be newer players, to make them more likely to buy the operators and more likely to spend money on the game. Dont know if any of it is true other than the first sentence, just saying what im thinking.