Any crypto exchange like binance, bitfinex and so on let you deposit and withdraw various ERC20 tokens.
Technically I don't understand how they implement gas fees when I withdraw? I deposited 100 TUSD and I was able to withdraw it without having any ETH in the same deposit address.
Once solution I can think of is, exchanges might be transferring ETH from a central wallet to this deposited address and then creating another transaction to transfer tokens. But this process will require 2 different txns which effects time and cost.
Any other solution? Anyone know how these exchanges do this?