I checked the debug.log on my bitcoin-data directory. Apparently the transaction was done on 4/15/20 02:39 local time. But during that time the bitcoin-qt is not running. What gives?
Well, a compromised computer would do the trick... If somebody has access to your wallet.dat AND is able to capture your keystrokes when entering the passphrase, he can rob you blind.
Could you post (part of) your debug.log? If the log entry was generated on 02:39 , it means your wallet was running at that point in time... However, like i said before: it's perfectly possible to spend your funds while your wallet is not running, the only thing a thief needs is the private key(s)... When he has the key(s) he can spend your unspent outputs at any time he wishes, he does not need your wallet to be online.
PS: posting your log can decrease your anonimity, but it does not contain information that will allow anybody to steal from you again.