Lol, this HAD to be a custom written transaction. This isn’t a mistype on the fee, this is a transaction that was only trying to move like 0.7 BTC, but didn’t write an output for the 19.8 BTC they expected to stay in their wallet.
ie. Someone wrote a transaction manually or was foolishly testing software and forgot to add a change address.
If only there was a bitcoin network...for testing...a testnet, if you will.
It can be the mining pool. Why put the change address if you can receive de coins back on the Coinbase transaction?! You can save some Sat's with that.
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