The Sims FreePlay sends a warning about the Quest, Discovery Quest, Hobby, or Event when 3 and 1 days remain, and when the Event is over but this warning also appears even if you have beaten the Event and obtained all prizes.
If you complete the Event and obtain all prizes, the Event does disappear from the Tasks list but the game still considers you are in the Event and thus still warns you that the Event will end. I don't know if this also happens with Quests, Discovery Quests, and Timed Hobbies. Usually it's unlikely you'll beat the Quest/Event before the 3 day notification appears unless if you were given a 2nd chance (the Event re-appears) or use a lot of LP which could be possible with Quests to speed up the time consuming tasks.
I'm guessing that Firemonkeys didn't want to bother coding FreePlay to check if the Event was beaten before displaying the notification or they wanted to save resources by not having the servers check every user's SimTown/device to see if the Event was completed so regardless if you completed the Event or even accepted it, you will still get the Notification. I'm also curious if this also occurs on Android and Windows Phone versions as well.
Origin ID: GothicSimmer, YouTube:
GothicSimmer0