FFLogs historical percentile changing

I noticed that my historical percentile has changed the next day after its upload.
Shouldn’t the historical percentile remain constant or does it come to a change when many new parses are uploaded on the same day?

Historical parses are computed in 24 hour windows (I can’t compute a real historical ranking for every last person in real time). You are compared against the state of the previous day until the next day’s parses have all been collected. This means there is a 1-time adjustment.