[DennisP]

Since you asked, here's where the terminology comes from.

The Ethereum VM has a bunch of different opcodes, some physically more costly than others. To account for this, each opcode has its own "gas cost." Storing a value costs much more gas than adding two values.

The gas price is the current price in ETH for one unit of gas. The gas price fluctuates with demand.

The transaction fee is the total ETH paid for your transaction. If you have a complex transaction that executes a lot of expensive opcodes, you will have a higher transaction fee than someone doing something simpler, even though you're both paying the same gas price.

[PebblesRox]

Sounds like the quote from the article is using the term "gas fee" to refer to the overall transaction cost. At least I don't see any reason why someone would specifically car about the gas fee portion of the overall fee in the context of losing most of the money in the refund process.

[DennisP]

Users focus a lot on the gas price since it's a consistent indicator of the cost to transact, so they've tended to use the terms "gas fee" and "transaction fee" interchangeably. Your transaction fee is used entirely to buy gas, which is spent in running your transaction.