When I click 'max' it doesn't show all of my ETH. Why?

All transactions on Ethereum cost a small amount of ETH to pay for gas, which covers the cost of processing each transaction. For a full explanation of how gas works on Ethereum, see here.

In order to make sure you have enough gas to complete your transaction, we subtract a small amount of ETH when calculating the “Max” amount you can stake.

If you're seeing your max as “0”, you'll need to add more ETH to your wallet or wait for gas fees to go down before you can stake.