If this was for an "Unknown" miner, I'ld include (a crappy form of) "mixing" as a possibility.

This is because the funds flow from a UTXO into the miner's fee (goes to the Coinbase transaction for the block). So a miner wanting to do mixing can include a transaction like this in a block they solve, knowing they get the fee.

But in this instance, that isn't likely the reason, as it was broadcast publicly, and included in the mempool seen by others, as seen in one of the replies to this Tweet:

https://twitter.com/_k3tan/status/1603302135877505024 [Nitter]