Networks and deposits
Gas
The unit measuring computational work on EVM networks, whose price varies with congestion.
Each contract operation consumes a fixed, known amount of gas. The total cost of a transaction is that amount multiplied by a unit price, which depends on demand at the second you send.
An ERC-20 token transfer consumes noticeably more gas than a native ether send, because it mutates contract state instead of moving a balance. That is the structural reason moving USDT on Ethereum costs more than moving ETH.