I got every part you told there, except ETH address.
How can someone be traced through it actually?
The possibility to be anonymous or pseudonymous relies on you not revealing any identifying information about yourself in connection with the bitcoin addresses you use. If you post your bitcoin address on the web, then you're associating that address and any transactions with it with the name you posted under. If you posted under a handle that you haven't associated with your real identity, then you're still pseudonymous.
Well, this also applied to Ethereum, right?
Who knows maybe an airdrop actually is a massive deanonymizing pool operated by an intelligence agency.
It depends completely on what and how we show our cards. Things like ETH are already centralized and it is proven many times, so the project conducting airdrop need not to be an intelligence agency because Vitalik has got too much control over these addresses that he will reveal everything himself to them if asked. The major cause for me to not take part in any of the airdrops is that most of them are ERC20 tokens working over Ethereum blockchain and no matter whichever project you give your KYC to for some dollars, your documents are assured to get compromised even if they show you huge privacy related content on their Privacy policy page. Most of them don't have an actual working concept and others are just clones with different names. I miss those PoW + PoS coins or just PoW coins that work on their own chain and had some real milestones to get achieved. Working for those coins was fun and they had value too, but these airdropped projects look junk to me and most of them prove out to be the same in future with no real use case.