This kind of transaction pattern is typical for Hive‑Engine. It’s not a hack and it’s not a bug — it’s simply wash trading or bot testing.
It’s important to remember that swap.btc is not that real BTC, but an internal pegged token that can be moved or traded between one’s own accounts at zero cost. Because there are no fees and liquidity is extremely low, even tiny self‑transactions can distort the charts, making it look like real market activity when it’s not.