I have withdrawn and trade ETH from MEXC multiple times already and I am never charged more than $3 but when I swap ETH ERC 20 on Uniswap the gas fee is almost always $10 and few times over $10, why is it like this? Are DEXs suppose to be more costly normal centralized exchanges?
With Centralized Exchange you are not actually interacting with the blockchain network, the fee was defined by the exchange and on CEX you only charged with trading fee there is no blockchain transaction fee. But with decentralized exchange you are actually interacting and using the Ethereum Blockchain so the fee was affected by the network condition. What you could do is checking the average transaction fee on the blockchain before doing any transaction on the DEX.