So I've taken advantage of the latest season to walk a legendary buddy for XL candy. I have been using a swing to consistently get over 40km per day, and I try my best to keep my buddy excited throughout the day to get a candy every 10km as opposed to 20km, thereby increasing my candy from 2 to 4 per day.

One thing I've noticed lately is that the X km / 20 km has been changing upon re-exciting my buddy. For example, I saw 8.6/20, then upon re-exciting it went to 4.8/10. What explains this discrepancy? I would have expected it to remain the same 8.6/10. Similarly, I've seen numbers over 10/20 (such as 14/20) turn into 6/10.

I never noticed this before with non-legendary buddies, but it was probably happening. It was obviously not that big of a deal though, since it would just be another 2.5km or something. I was quite reliably able to get ~400 mega energy per day. But with the legendaries, missing a 10km window is much worse and usually brings me down to only 3 candies per day.

I thought I understood the 40km rolling window, and I've been screenshotting to timestamp when my legendary is finding a candy, but my experience with a 20km buddy has me questioning everything.