Airdrop is one way to reward positive engagement but executing a perfect airdrop is challenging due to the Sybil attack problem. I don’t think we will ever be able to solve it in a fully decentralized manner, but we can continue experimenting to filter out bots from genuine users. Many projects have approached this persistent and ongoing issue in different ways. Some have used on-chain metrics, others have combined on-chain and off-chain metrics, and some have outsourced the process to the community (such as Hop and LayerZero).