How old does a message have to be in order for it not to show in the audit log by a bot?

I'm considering adding Carl bot to a server, and I want to know how long a message has to be if someone deleted it for it to show, and for it to not show in the audit log. I think I want to know for privacy reasons, since I would rather it not log every single of their messages they delete for example if it is 1+ months old. Sometimes people have gone on deleting sprees which I understand.

Would appreciate the advice if anyone knows, thank you!