Airdrop is just a short promotion by doing easy labor and earning a little money, but if a team asks to send them some ETH I will leave it, because I don't believe in the project.
It is indeed very commonplace to be left behind when an Airdrop asks for some ETH to claim the reward, but currently many who participate in the Airdrop don't get anything because the rewards that are distributed are very small for each participant.