I don't think anything wrong happened here.

5.94 BTC went to

bc1ql5lrt3y97djyu5k8ewmz87nnemxheycp6wdree
bc1qdplvug87leypur2a27xh64u8cu78e0td8edwv7
bc1qpa20zkg6kr55yl7gxnwh37aj8q00rt70k6q8ru

whereas 0.6610 BTC (10% of the prize) went straight to Binance (for cash out ?)

Someone helped the finder with the transaction and got 10% of the prize ?