lost weight a day after binging?

uhm so yesterday I may have eaten 3,500 calories after being in a 1300-1500 deficit for over a month (with a few 2000 cal cheat days), somehow today though I lost 0.2kg?? how does that make sense I’m baffled.

I mean I did walk cumulatively for like 3/3.5hrs yday since I was out with a friend. But surely that weight will be put back on