Case solved: If nothing unexpected happens, the address currently holding a long position worth up to $434 million in $BTC on Hyperliquid likely belongs to user "AguilaTrades".

My reasons:

1. The opening address (0x1f25...f925) on Hyperliquid has the nickname "AguilaTrades", which matches the name of the X account;

2. The $29.85 million margin used by the opening address (0x1f25...f925) was all withdrawn from Bybit, and "AguilaTrades" has previously shared on his Twitter multiple times about his large positions and profit rankings on Bybit. This indicates that Bybit is his commonly used CEX, which also makes logical sense.

He currently has a position worth up to $434 million on Hyperliquid:

20x long on 3956 BTC, position value $434 million. Opening price $108,638, liquidation price $103,287. Currently floating profit $4.45 million.