In case you’re wondering what happened, from the thread: He sent ETH to the WETH contract, received WETH as expected. Then he wanted to do the reverse and sent WETH, but will not receive anything, because you're supposed to swap your WETH to ETH in exchanges like Uniswap, or call the "withdraw" function in the contract. For contracts that want to only work with ERC-20 tokens, you use WETH, which comes from a contract…
So it's super-bad UX where radically different interaction patterns are used for what are to the user similar kinds of interaction, creating a trap.
This user unfortunately did neither.