I never give private key and I don't join airdrop that request Eth donation. Are there some other potential risk in joining an airdrop giving for examples my mail address, my twitter and telegram account and other basic information? I also use dedicated profile to join them. Thanks!
The only risk that i can think is they will know your email address, but you can prevent this by using other email and if the airdrop is limited to a few participants, there's a high chance that you'll enter your private key instead of the address if you are in hurry and don't recheck what you type in the form. Other than that, there's no risk because it's free, you don't need to pay anything to join.