I sent 100 coins at 11 am through Bitcoin core a wallet, and exactly the same number of 100 coins were sent to another address at about 3 pm.
But I did not send 100 after 3 hours.
If I were hacked, I had more than 200 existing balances, but it only paid 100 withdrawals.
Of course, the wallet.dat file never leaked outside. I used Messenger on my computer, but I did not surf the web at all.
If wallet.dat is leaked, I would have withdrawn all the remaining balance, but it is not because I have withdrawn only 100 pieces.
Have you ever seen such a hacking technique?