I was supposed to mark my bosskill time too, but I completely forgot about that

I believe the vic screen counter stops when you kill your last boss, but the daily timer only ends when you go to the exit. So if you do anything between the two, that will show up as a difference.
I didn't do anything noteworthy this run, tried to play as casually as possible, popping Yendor and killing only +1 foes, but before I noticed I was back to +3 kills
