Parachain Swap's airdrop has been quite controversial as it only rewarded a small portion of its users. The vast majority of the people weren't rewarded (especially airdrop hunters), resulting in a decline of the token's price.
ParaSwap distributed PSP tokens to early users in value of $150 million. Actually, terms of getting airdrop were not transparent and it is still unknown how they chose people who get tokens. The ParaSwap dex aggregator has been launched its own PSP token. In honor of this event, the team made a major airdrop to their users. Unfortunately, only about 20 thousand users of the platform received a drop of 150 million coins (7.5% of the total amount of coins). Personally I hadn't used this platform actively, so I was not disappointed that I didn't get anything, but there are a lot of people who just live on this platform and they also didn't get anything.