People above 4k who opened the game before the update did not receive their season reward (the draft chest) while people who waited until after the update did.
This seems unfair to those of us who didn't think they'd miss out on the reward just for checking the app.
Edit: Some people are reporting that they didn't receive a reward after the update, while others are reporting that they did (example). What seems to be the case at least is that if you opened your app and saw your end of season ranking before the update, you don't have a possibility of obtaining the reward, but if you wait until after the update you do.
Edit2: Two of the confirmed cases of receiving a reward were just below 4k before the reset, then won a match which brought them over 4k after the update, which triggered a trophy reset and gave them the reward. This may just be a bug, if you received one please leave a comment stating if it was the same for you.
Edit3: After all the feedback it seem like the only people who received a reward were those described in edit2, so don't feel too bad for not getting a draft chest since most people didn't. We just need to wait for feedback from /u/ClashRoyale to confirm.
Edit4: The mystery continues… now someone has confirmed that they didn't receive a reward at first, but they dropped below 4k and climbed back up, which caused them to receive one. I just tested it and it didn't work for me, but maybe it will work for others.