Reacting to the first paragraphs: on decentralized exchanges, traders (liquidity takers) don't change the price because of something called the constant product formula. Market makers (liquidity providers) do.

Since trading doesn't impact price, front-running can't be done by sandwiching buy/sell orders but with LP orders.

Also slippage isn't price movement due your own trading (that's price impact). Slippage is difference between displayed price the moment your press trade and price when order is processed at exchange (due to other people's trading during network delay).