First time wallet drained

I created a wallet and funded it. I used it for an open source bot. I tested with a small amount everything seemed fine. I added more funds everything seemed fine. I let the bot run over night and approximately 5 hours later was drained. What is the most likely attack vector?

Clean PC almost brand new with no other open source clones. No sign of a key logger and that I would think would drain immediately. Private key added to bot which could obviously be problematic but again would happen immediately. Confused as to how a drainer gets executed hours later or randomly. Any thoughts?

Edit: Here is the bot used - https://github.com/DefMet/Arbitrum-sniping-bot-arbx

I've communicated with someone behind the bot and they looked into it and tried to help me out. Obviously an open source bot is a risky thing. I didn't see anything in the code, but I'm not a dev. Tried to run it through chatGPT but too long. As stated transferred small amounts with no issue ran the bot with no issue. Added more funds no issue... what I am getting at is that most attacks would happen immediately and this one waited for hours before taking action. I don't want to jump to conclusions, so trying to see if there is any other way I could have been compromised before blaming the bot devs even though that is most likely the culprit.

The funds are still sitting in the wallet they were sent to untouched. So this whole thing seems super weird