Breaking it down|Slippage is not a fee.
The difference between the price you see when placing an order and the average execution price is called slippage. Insufficient order book depth, a large order consuming liquidity across multiple price levels, or price changes in a liquidity pool while an on-chain transaction is pending can all cause slippage.
Slippage tolerance is the maximum price deviation you’re willing to accept; it is not a price the platform guarantees you’ll get. Setting it too high may mean accepting a worse price and increase the opportunity for sandwich attacks. Setting it too low may cause the trade to fail, and you may still incur gas costs on-chain.
Check the depth, quoted price, and minimum amount received before deciding whether to trade. A limit order can constrain the price, but it does not guarantee execution.