Quest rewards will now be based on the league you are in when the quest is finished.

What does that exactly mean? Does one receive less cards in lower leagues?

Previously the rewards were set when the quest was started, but this led to some players achieving higher leagues and then purposely dropping down in ranking to complete their quests easily.

I always automatically (but not intentionally) drop in ranking when trying to fulfill the quests because it means I cannot use my only strong splinter.