Fees
Staking on a subnet is a swap against that subnet's pool, and every swap pays a fee. The default is about 0.05%, and each subnet can set its own rate. When you stake, the fee comes out of the TAO you put in. When you unstake, it comes out of the alpha you sell.
Some moves cost less. Moving stake from one validator to another within the same subnet is not a swap, so it pays no swap fee. Moving stake from one subnet to another runs two swaps but charges the fee once. Staking on root converts one to one and has no swap fee.
A small network transaction fee applies on top of the swap fee, since most actions on the chain carry one.
Wallets show the fee in the order preview before you confirm. On large orders, the swap fee is usually smaller than the price impact of the trade itself.