It could be a sign of the scam because, as far as I know, the airdrops participants don't need to send or transfer any ETH to any address from the project. After all, the teams will send the token to the participants after the program ends. As long as the participants fill the requirement, the token will be sent to their address without transfer some amount of ethereum. So we hope that you don't transfer any amount to them because they will run away after they get your funds in their wallet. Be careful with another project that similar to that one.