Because it isnāt a computer program that will end exactly in 21 days 13 hours and 10 sec š
I donāt know if you understand me lol š. Itās mostly an Indica dominant, Indicaās flowering period is short, around 55 days to 60 days and sometimes for the longest one around 65 days to 70 days, it isnāt an exact science bro. But for sure, yours is nearly done, perhaps another 2 weeks more.