thousands of new players are cheating at puzzles
70000 people earned >2200 puzzle rating in 4 days? When only 15000 people had that prior to Christmas? Tell me you don't know how to math without telling me you don't know how to math.
I've thought of another possibility: these people were always there, but the system wasn't counting them as existing prior to them using it for the first time since the rating system change in October, and this is the first time large numbers of people are getting to do puzzles due to the holidays. Though then the numbers should be leveling out soon.