im still a tad new to all this, i've been mining eth and i have almost a full eth so far, but i noticed that you can get 4-5% apy on eth by sending it over to blockfi.
Honestly, don't. If you want to stake your ETH, how about using
lido.fi or another ETH2 staking solution? Right now, Lido is offering 5.7% and, AFAIK, they are the top 2 "staking pool" on the entire network with over 334k ETH. You can swap sETH to ETH quite easily through Curve, so there is no lockup.
Any reason to NOT do this? Is it stuck there permanently in some way or limited on when / how soon you can withdraw if you need to quickly?
BlockFi is known for taking a bit to process withdrawals. They may or may not ask you to send them a verification selfie and they may or may not delay your withdrawals. They also don't process them on the weekends or holidays.
They are also entirely centralized, so you're risking your coins since they could get hacked, freeze your account, etc... better to go with a trustless solution (in the case of ETH).